(written from a Production point of view)
A scientific team in the Arctic discovers two mysterious cyborgs, similar to those described by Zefram Cochrane. When they assimilate the scientists and move into space, Enterprise is called upon to find the cybernetic beings and stop them.
The Arctic, Earth. A scientific expedition is in progress. A transport flies in a research team. Three Human scientists tramp through the snow, holding scanners. Their names are Drake, Rooney and Moninger. They find what they seek: the crash site of an alien craft.
They break up, searching in different directions. Rooney picks her way quickly but carefully through debris and snow, until her scanner starts beeping. She stops, kneels and brushes away snow, uncovering something. She calls her comrades over to see what she has found.
The scientists comment on the creature's humanoid appearance and how well preserved it is. Drake, the leader, calls in for a base camp to be set up. Then Rooney gets another reading, goes to the spot of its origin and finds another frozen cyborg.
Later, with the camp set up, the two lifeforms have been placed on tables in a laboratory. They are covered, neck down, in a black exo-plating. Moninger examines them, while Rooney examines a small piece of the ship's hull.
They show Drake their findings. Moninger, after examining a bulky cybernetic prosthesis that one of the lifeforms had on its right arm where the forearm should have been, has found that it had been integrated into the creature's circulatory and nervous system; it could have probably controlled the device as if it were its own flesh and blood. He has also examined the eyepiece of the first discovered individual, and has found that with it, the creature could have seen most of the EM spectrum. Rooney finds that their ship crashed about a hundred years prior. Drake instructs them to transmit the findings to Starfleet.
But as they speak, they hear a mechanical whirring, and see the tool at the end of the cybernetic prosthesis whirring and clicking. After a hundred years, frozen in ice and snow, it still works. A further examination of the prosthesis is in order.
Moninger does the examination, looking at a bit of the tissue from the part of the prosthesis that was attached to the lifeform's arm under a microscope. He shows Drake. Microscopic machines, some form of nanotechnology, are among the cells, repairing them. There are thousands of them in each creature. Not only are they regenerating the tissue, but they are repairing the mechanical parts on a microscopic level. The prosthesis is fully functional, with Moninger calling it "as good as new."
As incredible as he finds this, Moninger also finds it disquieting. How far will this regenerative process go? These creatures do not look very friendly. What if they are fully revived and prove dangerous? And just what were they doing on Earth a hundred years ago? Did they come in peace or otherwise? He suggests that, just to be on the safe side, they freeze them again and examine them under more controlled conditions.
But Drake says no; re-freezing might damage them. They will remain in the laboratory and the regeneration will be allowed to continue. He goes outside to where Rooney is further investigating the ship's debris.
Meanwhile, another researcher brings a flask of a hot beverage for Moninger in the lab. Before he leaves, he looks at the two lifeforms and voices concern; will Moninger be alright? Moninger assures him that he will, showing him a rifle he has for protection.
Alone again, Moninger pours a cup of the beverage. Then he hears a mechanical clicking noise from one of the lifeforms. Alarmed, he checks the monitor that displays the lifeform's neural activity. Nothing.
Inside the lab, Moninger still watches the monitor. Then, suddenly, a spike appears. Then more spikes, then full signals; neural activity has begun in the lifeform's brain. The lifeform awakens with a gasping breath. Moninger grabs a scanner and begins scanning it, as it opens its organic eye. Its mouth closes and its face lapses into a cold stare, as it beholds him.
Outside, Drake and Rooney hear his scream and see the light beams of his weapon.
They rush back to the lab, which is now ruined, with two large streaks burnt through the walls from the rifle and all the equipment thrown to the floor. They find one lifeform on the table where they left it, while the other is gone. And they find Moninger behind some tossed-over shelving, gasping painfully. The left side of his face is streaked with black, mottled lines that are spreading, as the nanoprobes that the revived lifeform injected him with move visibly under his skin, multiplying rapidly and assimilating him. Drake tells Rooney to get a medical kit. She turns to do so, and turns right into the revived lifeform, its organic eye staring at her coldly, the red laser light of its eyepiece on her face.
Three days later, at Starfleet Headquarters, Commander Williams rushes into the office of Admiral Maxwell Forrest. He informs the Admiral about the prolonged loss of contact with the research team. Forrest orders him to ready a shuttlepod. He and an armed team go to the site. All they find is snowed-in, abandoned shells of structures; no sign of the research team or the debris from the crashed ship.
Out in space, aboard Enterprise NX-01, Captain Jonathan Archer speaks to his senior staff in the situation room. Admiral Forrest has informed him of what has happened and has sent him the data the scientists gathered, believing the creatures abducted the research team. The transport the team used was detected leaving Earth at warp 3.9.
This shocks the chief engineer, Commander Tucker; these transports cannot exceed warp 1.4. Archer surmises that the "aliens" improved the ship's systems using technology from the wreck of their own ship. The transport's projected course puts it within six light years of the current position of Enterprise. Forrest has ordered that they intercept it and rescue the research team.
Sub-Commander T'Pol surmises that isolating the transport's warp signature should not be difficult. Archer decides that the search should start at specific coordinates, which he inputs onto the table's display. He orders a tactical alert and orders Ensign Travis Mayweather to lay in the necessary course.
As the ship heads for the area, Lieutenant Malcolm Reed, the armory officer, speaks to Doctor Phlox, the chief medical officer, about the "aliens" possible weapons. He and Phlox look at the research team's biometric data on the creatures, but find no evidence of weapons. This worries Reed; the team was well armed; how did these two "aliens" manage to overpower them without weapons?
Enterprise continues toward the coordinates. Captain Archer is in his ready room, reading something on his computer terminal. Then T'Pol calls him to the bridge; they are receiving an automated distress call from a Tarkalean freighter. He goes out onto the bridge, where Ensign Hoshi Sato at the communications station tells him what the message says: the freighter is under attack. He orders Mayweather to alter course toward it.
The freighter is banged up and dead in space. The transport, heavily modified now looks very menacing, far from the ordinary-looking vessel it originally was. It is cutting into the freighter with a cutting beam.
Enterprise arrives. Archer orders a hail to the transport, warning to cease and desist immediately or be fired on. The transport responds with a volley of proton bursts at Enterprise. T'Pol scans nine Human life signs on the transport, but the readings are erratic. Reed believes he can disable its weapons; Archer orders it done. Enterprise fires on the transport, which breaks off its attack and takes off at warp. Archer orders a shuttlepod deployed to the freighter to bring the survivors aboard.
The survivors, two in all, a man and a woman, are lying unconscious in sickbay. Their faces and hands are marred with emerged implants. Archer and T'Pol are present. Phlox informs them that the two should live, but then shows them what is happening to them: the nanoprobes in their bodies are transforming them into "some sort of cybernetic hybrid." T'Pol surmises this as the reason for the erratic Human life sign readings; the research team is likely being similarly transformed.
Archer asks if the nanoprobes can be removed. Phlox says no; they are multiplying extremely fast; he could never remove them all. T'Pol advises that the two should be secured in the decon chamber. But Phlox makes the same terrible mistake the research team's leader made; he says that he cannot treat them properly there, and he does not believe them to be a danger to the crew. However Archer is not so sure. He will have Reed post a guard.
Later, in Archer's ready room, T'Pol comes to tell him she has contacted Tarkalea and informed them of their rescue of their people. Archer shows her what he was reading before. It is a speech that was given at Princeton University 89 years prior by the inventor of Human warp drive, Zefram Cochrane. In it, he had spoken about the events surrounding his first warp flight, and of a group of cybernetic creatures from the future who had intended to "enslave the Human race". They had tried to prevent the flight but were stopped by a group of Humans, also from the future.
T'Pol reminds Archer of Cochrane's over-active imagination and the fact that he was frequently drunk. Archer acknowledges this, saying that nobody took the story seriously and Cochrane recanted the whole thing years later. But there are similarities between the story and these current events that cannot be ignored. And if the story was indeed true, then these creatures may be heading back to where they came from, so that another attempt can be made.
In sickbay, the two Tarkaleans begin to stir. Phlox goes to the male, who wakes up very agitated on seeing him. He demands to know who Phlox is and his location, and is horrified to see the implants in his hands. Phlox tries to calm him down, then picks up a hypospray with a sedative to administer it to him, as he suddenly convulses and screams with pain.
But then, as Phlox comes close, the implants take full control of their victims. On the other biobed, the woman rises behind the guard Reed posted in the room. The man grips Phlox' arms with incredible strength, and the woman throws the guard all the way across the room. The man forms a fist and brings it to Phlox' neck. Assimilation tubules dart out, injecting Phlox with nanoprobes. He throws Phlox over the bed. Phlox collapses in a heap on the other side, unconscious.
The two Tarkaleans leave the room via a maintenance shaft ladder. Meanwhile, the skin around the injection point on Phlox' neck starts to change color, as the nanoprobes begin the process of assimilating him.
While unconscious, Phlox begins hearing the Collective's hive mind. However, this is stopped, when Archer wakes up Phlox. Reed is present with Archer, along with security officers, all well-armed. Phlox quickly scans his neck and confirms what has happened; he has been infected with the nanoprobes. Scans by the security officers reveal the route the two Tarkaleans used to leave. Archer orders Reed to seal off the maintenance shaft, post guards at every access point, and find and subdue them. Phlox warns Reed about their greatly enhanced strength and to avoid being touched by them. He then scans the security officer who was with him when the attack happened, and confirms that he hasn't been infected. Archer orders the officer to keep guarding sickbay.
Meanwhile, the two Tarkaleans move through maintenance shafts, never rushing, but moving quickly nonetheless. They come to a set of wall panels, remove the covers and inspect the circuitry.
In engineering, Commander Tucker shows Captain Archer scans of the modified transport. It has been greatly enhanced, with more powerful engines, hull plating, weapons, and other modifications Tucker cannot even guess the functions of. Archer notices that the aft plating has not yet been enhanced; a couple of torpedoes should break through and knock out a nearby EPS manifold, disabling the ship.
Then T'Pol calls from the bridge; she has detected the transport, less than two light years away, moving at warp 4.8; a significant development; its top speed has doubled in less than twelve hours. Archer orders Ensign Mayweather to alter course to intercept it.
Meanwhile, in the maintenance shaft, Reed and his security officers move carefully, looking for the Tarkaleans, using scanners to track them down. They find displays that, instead of showing what they should, are filled with strange green script on black backgrounds.
They come upon the individual that used to be the Tarkalean woman altering more panel circuitry. It is seen plunging its assimilation tubules into the circuitry, which instantly morphs into modified technology, taking on the familiar black and green color. Reed sternly and repeatedly orders it to stop, but it continues after a cursory glance at them. They fire their weapons at it. The shots merely make it lose balance a bit, and subsequent shots hit nothing but personal shields. They crank the weapons up to maximum power and fire again but fail to pierce the sheilds.
However, their attacks cause the Tarkalean to register them as a threat. It turns and advances on them. Remembering Phlox' warning, they quickly withdraw, only to run into the cybernetic lifeform that used to be the male Tarkalean. It overpowers one of them and tries to inject him with nanoprobes. With its tubules shooting out mere inches from the guard's head, Reed whacks it in the head with the butt of the officer's fallen phase rifle, temporarily stunning it. He calls the bridge and reports the location of the two to Captain Archer, and that they appeared to have been modifying systems. Archer asks T'Pol what is in that area. Her answer: warp plasma regulators, essential for the warp engines to function.
Suddenly Mayweather reports the destabilization of the ship's warp field; they are falling out of warp. The assimilated Tarkaleans have disrupted the regulators. Without warp, Enterprise has no chance of ever catching the transport. Archer recalls that there is an outer hatch in that area. He orders Reed and his officers to clear the area and seal it and orders Ensign Mayweather to bring Enterprise out of warp. When this is done, he orders T'Pol to open the hatch. The two Tarkaleans are instantly blown out into space. At Archer's order, T'Pol closes the hatch and re-pressurizes the area.
He is dismayed at having to resort to this, but T'Pol tells him he had no choice. Archer orders course for the transport resumed, and orders Reed to work with Tucker to find out exactly what the two were doing to the systems.
In sickbay, Ensign Sato, who is wearing a phase-pistol at Malcolm's insistence, brings food for Phlox and his small menagerie of little alien animals. He accepts her offer to feed the animals, but he will not eat himself, for fear of accelerating his metabolism and causing the nanoprobes in his system to spread even faster. He now has a sickly white and black-mottled patch over the tubule wounds. She desires to stay and keep him company once she finishes but he insists that, for her own safety, she leave immediately when done. "I underestimated these nanoprobes once; I do not intend to make the same mistake twice," he tells her.
Meanwhile, Tucker and Reed examine the modified circuitry but they cannot determine what has been done to it.
Captain Archer goes to the mess hall. T'Pol is there. She advises him that perhaps it is better not to try to rescue the Humans, saying that it is logical to assume that all aboard the transport has either been transformed or are transforming and that bringing any of them aboard may be extremely dangerous. The transport should be destroyed, she adds. But Archer is not ready to do this. Then Phlox calls him, asking him to come to sickbay.
His condition has worsened. His hands tremble, the patch on his neck has spread over the entire right side of his face, a second patch has formed on his forehead and a third is forming on his right hand. He tells Archer that his Denobulan immune system seems to be baffling the nanoprobes, but they are persistent and will adapt and keep multiplying. Eventually, he will be transformed. However, he has found a possible treatment. Their processors appear to be susceptible to omicron particles. Exposure to this may destroy them and cure him, but the level has to be very high, lest even one nanoprobe survive. Such a high level would be very painful.
Should it fail, he has one surefire cure: death. He gives Archer a hypospray containing a neural toxin that will almost instantly end his synaptic functions, and asks him to use it if the treatment fails. Archer is shocked, but Phlox is resolute: he will not allow himself to be turned into one of these "cybernetic creatures".
In the armory, Reed and one of his security officers test modifications of phase-pistols to try to get them to penetrate the personal shields. A particular setting works. They begin modifying as many weapons as they can. They work quickly; Enterprise will catch the transport in less than an hour.
Sure enough, less than one hour later, they come upon it. Its defenses have been further enhanced since their last meeting. It accelerates almost to the limit of Enterprise's speed, warp 5. Archer orders speed increased to match. The ship begins to shudder with the effort, but they close the distance. Archer orders Reed to target the EPS manifold that he and Tucker agreed on.
The transport drops out of warp. Ensign Sato reports an incoming transmission; it is an activation sequence. On Archer's order, she tries to stop it, but cannot. The Borg-modified circuits suddenly become active. Main power and other systems, including weapons, begin to fail. Archer angrily realizes the truth: the assimilated Tarkaleans sabotaged the circuits, modifying the appropriate systems so that this signal would cause them to fail.
Then Sato reports a hail coming in. Archer orders it answered. He angrily begins to identify himself and Enterprise. But he is cut off. Cut off by words spoken in a cold, soulless, multi-track resonant intonation: "You will be assimilated. Resistance is futile." The transport closes ominously on Enterprise.
The transport hammers Enterprise with weapons fire, wearing down her defensive polarized hull plating. Commander Tucker feverishly works trying to undo the sabotage so that they can at least regain use of weapons, but it will take several minutes. Captain Archer gets an idea. He asks Reed if the transporter is still working. It is. He orders Reed to come with him, telling T'Pol to be ready to beam them off the transport.
Meanwhile, in sickbay, Phlox' condition has worsened considerably. Both sides of his face now look cybernetically enhanced, as well as both hands. He again hears voices in his mind. His movements are hunched and painful. His voice is tremulous. But he determinedly sets up the omicron treatment, telling the guard to activate it once he is in the imaging chamber. He gets in. The guard activates it. Lights strobe over Phlox. He grimaces and grits his teeth in agony.
Captain Archer and Lt. Reed, armed with Reed's modified phase-pistols, beam onto the transport. Its interior has been completely assimilated and modified, including the presence of alcoves. They carefully pass by regenerating individuals. Archer scans for any possible victims to be rescued.
The transport continues to hammer Enterprise.
Suddenly, two assimilated lifeforms round a corner and march toward them. They fire, unaware that they will be ignored as long as they do nothing threatening, and they drop. The two men check them. One of them is a scientist from the Arctic. On scanning them, Archer realizes that he labors in vain to rescue them, or anyone else on the transport. These two are no longer Human. The one he scans used to be Rooney.
Then more lifeforms round the corner, having registered them as a threat due to their previous action and advance on them. They withdraw, making their way to the EPS conduit they tried to destroy before.
Meanwhile, things get much worse on Enterprise as six individuals board her. T'Pol, as first officer, dispatches security to try to stop them, but the officers experience the same result as Reed and his team did against the individuals that used to be the Tarkalean woman: their shots kill two, then hit nothing but force fields on the remaining when they adapt. The individuals advance relentlessly, pushing the officers ever backward. Meanwhile, Commander Tucker manages to isolate one of the power relays and begins to reroute power to the engines and weapons.
On the transport, Archer and Reed continue toward the conduit, killing the lifeforms that try to stop them. Each one Archer scans confirms unrecoverability. Reed's modifications of the pistols work for now; they kill several. But it will not be long before they adapt. Reed is briefly lifted against a wall by the neck, only for Archer to kill it by ripping out the wiring on its head. They find the conduit and Reed quickly places charges on it while Archer fends off advancing individuals.
At the same time, Enterprise's polarized hull plating finally fails and the transport begins to use its cutting beam on her hull.
But Archer and Reed succeed in mining the conduit. Just as the individuals finally adapt to their weapons, he has T'Pol beam him and Reed back. As soon as they materialize on the transporter platform, he has Reed detonate the explosives. The desired effect is achieved: the transport's power is disrupted. The cutting beam stops. At the same time, Trip manages to disable the alien circuitry on Enterprise, restoring power to the systems. Returning to the bridge, Archer is asked about the research team by T'Pol. He tells her there is no longer anyone aboard they can help.
But then the individuals that boarded Enterprise beam off. Reed reports with alarm that the transport's systems are being restored; it is charging weapons. Archer is now versed enough in what they are dealing with to know exactly what to do; he orders full weapons directed at the transport's warp core. Enterprise fires all her weapons at the transport, which explodes as she quickly departs. The transport destroyed, he grimly orders Sato to contact Admiral Forrest before going off to his ready room.
Later, with Enterprise having resumed its original course, Archer and T'Pol go to sickbay to see Phlox. He has fully recovered; the omicron treatment was successful.
But Phlox has ominous news; he tells them about the "strange experience" he had while he was infected; the voices in his mind, as if he were part of a collective intelligence. T'Pol suggests he hallucinated it. But he does not think so; he got the distinct impression the "aliens" were trying to send a subspace message: a numerical sequence he heard over and over again. He gives them a PADD with the numbers.
Later, T'Pol goes to see Archer in his ready room. He has had the computer analyze the numbers. The results have him even grimmer than before. They are the spatial coordinates of Earth - the aliens sent a message detailing Earth's location. T'Pol asks him where the message was sent to. His answer: deep inside the Delta Quadrant. T'Pol tells him that there is no immediate worry as a subspace message would take at least two hundred years to get there, providing it even makes it at all.
"There's no reason to assume they're hostile."
"They don't exactly look friendly."
- - Drake and Moninger, discussing the frozen drones
"You seem a little jumpy."
"Cybernetic corpses, digging through frozen remains in the middle of the night. Why would I be jumpy?"
- - Drake startles Rooney after they find Borg in the Arctic
"Buried in the ice for a century."
"Hard to believe anything could survive."
- - Tucker and Archer viewing images of the Borg taken in the Arctic
"What sort of people would replace perfectly good body parts with cybernetic implants?"
"You, of all people, should be open-minded about technology."
"Well, I don't have a problem with it… so long as it stays outside of my skin."
- - Reed and Phlox
"Use extreme caution, Lieutenant, their physical strength has been enhanced. It is critical that you do not let them touch you."
- - Phlox, having been injected with nanoprobes
"…, you will be assimilated. Resistance is futile."
- - The Borg
"I doubt there's any immediate danger. It would take at least 200 years for a subspace message to reach the Delta Quadrant, assuming it's received at all."
"Sounds to me like we've only postponed the invasion, until what… the 24th century?"
- - T'Pol and Archer
- Filmed: 27 February 2003 – 8 March 2003
- Second unit filming: 11 March 2003
- Premiere airdate: 7 May 2003
- When the assimilated transport attacks the Tarkalean freighter, and later Enterprise, it is seen cutting a circular chunk into their hulls. This was an allusion to the TNG episode "Q Who", when the Borg take a cylindrical cross-section of the USS Enterprise-D. The writers had initially hoped to show the cylinder being tractored away from the Tarkalean freighter, but this effect was deemed too expensive. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- Because of David Livingston's often quick directing style, the filmed episode was several minutes too short. Several scenes had to be written in including the scene with Reed and Phlox in the armory talking about the weapons of the Borg, the phase-pistol efficiency test scene with Reed and Alex in the armory, and the scene in the base camp with Rooney scanning the debris of the sphere. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- However, when confronted with the script some production (fan) staffers were initially less than enamored, or as Production Illustrator John Eaves has put it, he being called upon to design Arctic One and its subsequent "Borgification", "During Season 2 of Enterprise we got wind of a future script #49 called "Regeneration". Everyone in the art dept.… started to read the little teaser and we all gasped in Horror at about the same time, THE BORG!!! NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!. We all were not feeling to happy about this new TNG alien showing up in an episode of Enterprise before Kirk… well this will throw all lines of trek history out the window. A few days later the first script arrived and reluctantly we all went to our desks and read away… Hey this is OK I thought It does work and it ties into Trek history as defined in "First Contact". As you recall The Borg sphere went back in time to destroy the Phoenix warp ship thus changing earths history and killing the threat of Humanity in the future. The Sphere gets fired upon by the Enterprise-E and the evil plot is eliminated… Now we are working on Enterprise and this new story picks up on the debris from the sphere being discovered in Antarctica. like "the Thing" once thawed out the Borg go back to doing what they do best! Assimilation! My job on this one was to create an Arctic exploration vessel that makes the discovery and later becomes Borgified. The first sketch is high profile vessel that I thought when Borged could form a cube. This idea was passed on and the second sketch got the approval. The ship is lightly based on a stylized snow mobile. Once Borged it goes thru a variety of changes and this second sketch try’s to convey on of the stages of coverage. Pierre over at Eden modeled this one." 
- Arctic One as it appeared in the beginning and Borgified was illustrated by John Eaves and rendered in CGI by Pierre Drolet. 
- The ENT Season 2 Blu-ray features the special "Outtakes" in which two scenes from "Regeneration" can be seen from a behind the scenes view. The first scene includes the talk between Archer and Tucker in engineering and the second scene includes some goofing around in sickbay with Scott Bakula, Dominic Keating, John Billingsley, and Paul Scott.
- The second season Blu-ray release also features seven production stills from "Regeneration" in the special "Photo Gallery". These shots include David Livingston on set, approaching Borg drones in a corridor, the three Arctic scientists, Reed climbing up the ladder, and stills of Vaughn Armstrong, Brian Avery, and Mark Major.
- The simulated snow for the Arctic Circle set was previously used as salt for the Rura Penthe set in the second season episode "Judgment". (Star Trek Monthly issue 108, p. 39)
- Among the debris in the Arctic Circle is a filming model of the USS Enterprise-E's front saucer section, originally created for the crash sequence in Star Trek Nemesis. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- The maintenance shaft sets were later re-used as corridor sets of the USS Defiant in the episodes "In a Mirror, Darkly" and "In a Mirror, Darkly, Part II" and of the Romulan drone ship in "Babel One", "United", and "The Aenar". ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- A power distribution node from inside the assimilated Arctic One was later sold off on the It's A Wrap! sale and auction on eBay. 
Props and costumes
- The arctic gear suits seen in this episode were designed by Robert Blackman. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- Bonita Friedricy's arctic archaeology team coat was later sold off on the It's A Wrap! sale and auction on eBay.  Her Borg costume was sold off at the 40 Years of Star Trek: The Collection auction at Christie's. 
- The arctic gear outfits of Chris Wynne, Adam Harrington, John Short, and Vaughn Armstrong were also sold off on eBay.     The boots worn by Armstrong featured a brand tag from North Face. In addition, an arctic gear undershirt, worn by Jim Fitzpatrick and also by John Billingsley, Connor Trinneer, and Vince Deadrick, Jr., was also sold off. 
- The costumes of the two Tarkaleans, played by stunt actors Mark Chadwick and Nicole Randall, were sold off on eBay. Their costumes featured several attached Borg skin pieces and Borg implants.    
- Two pairs of the prop charges seen at the end of the episode were sold off on the It's A Wrap! sale and auction on eBay. They were later re-used as stun grenades by the MACO in the third and fourth season.  
- The medical scanner of the Arctic Team was a re-use of Daniels' Temporal Observatory device from "Cold Front" and was also sold off. 
- Other props from "Regeneration" which were auctioned include the prop Borg arm,  an Earth Science Institute communicator,  and a medical report PADD. 
- The remote control used by Reed at the end was previously used by Trip Tucker in the episode "Marauders".
Cast and characters
- Bonita Friedericy, who played Rooney in this episode, is the wife of Phlox actor John Billingsley.
- In an audio commentary for "Regeneration" on the ENT Season 2 Blu-ray, Friedericy and Billingsley joked that Friedericy got the part of Rooney by sleeping with Tucker actor Connor Trinneer. In reality, Friedericy auditioned for the role of Rooney, but when she walked into the room to audition, Star Trek: Enterprise creators and Executive Producers Rick Berman and Brannon Braga pretended not to know her. "It was very unnerving, because I'm very shy and I didn't know whether I should say hello or not," Friedericy explained. "So, I sort of waved at them and they both kind of looked distastefully at me, and looked up at the ceiling and then they said, 'Go,' and I thought I wasn't gonna get it, and it was sad, but then I got the call and I got it."
- On the set, Friedericy was referred to as a baby Borg. "I was called the baby Borg because Borg are never little, and I'm five-foot-three," she remarked. Applying the Borg makeup to Friedericy for Rooney's assimilated appearance took five-and-a-half hours. This was longer than usual because the makeup team, not having done any Borg for a while, initially made a mistake with Rooney's Borg makeup. To portray the assimilated Rooney, Friedericy also wore a Borg costume that Roxann Dawson had previously worn, in VOY: "Unimatrix Zero". Once Friedericy was made to look Borg, it was time for her to go before the cameras as the assimilated Rooney. Filming the character's death scene didn't require a stunt performer. "I was really pleased with myself," she reminisced, "because they squibbed me [repeatedly], and I did my own stunt." Each time Friedericy performed the stunt sequence, John Billingsley applauded her from off-camera. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- Writer Mike Sussman expressed the remarkable likeness of Phlox actor John Billingsley and his stunt double Vince Deadrick, Jr. who not only was the Stunt Coordinator on Enterprise but also the regular stunt double of Jonathan Archer actor Scott Bakula. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- Background actor Louis Ortiz played one of the two Arctic Borg drones. He also played several Borg drones in the prequel, Star Trek: First Contact, and appeared numerous times as a Borg in Star Trek: Voyager. On set he was known for teaching actors how to move like an alien and behave like a specific species. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- This episode marks stunt actor Paul Scott's first Trek appearance. He will make two more in the third and fourth season, though uncredited.
- This episode is a sequel to the events of Star Trek: First Contact. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- The Bynar species, which first appeared in the Star Trek: The Next Generation Season 1 episode "11001001", are mentioned in this episode by Phlox as being an example of an admirable use of cybernetic technology.
- The oft-mentioned Tarkaleans, first named in the Star Trek: Deep Space Nine episode "Past Prologue", make their first and only on screen appearance in this episode.
- The invasion that Archer predicts does indeed happen in the 24th century, in 2366, 213 years after the events in "Regeneration", in TNG: "The Best of Both Worlds".
- This episode contains the only mention of the Delta Quadrant in the entire run of Star Trek: Enterprise.
- This episode shares a similarity with "Acquisition" in that the antagonists remain unnamed, though they are a well established species within the Trek universe. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- Reed's line about shooting the Borg drones with holographic bullets was an in-joke by the episode writers. In the holodeck scene in Star Trek: First Contact, drones could indeed be killed by holographic bullets, assuming the holodeck safety protocols were turned off. ("Regeneration" audio commentary, ENT Season 2 Blu-ray)
- Archer's method of physically disabling one of the Borg, by tearing some of its wires out, is reminiscent of the way Captain Picard disabled a Borg in TNG: "Descent, Part II".
- This episode includes the only appearances of the Borg in Enterprise. Similarly, the Star Trek: Deep Space Nine pilot episode, "Emissary", was the only appearance of the Borg in that series, although the USS Defiant was among the defense fleet against the Borg during the Battle of Sector 001 in Star Trek: First Contact.
- For the sequence outside of Starfleet Headquarters, a recurring moving matte painting was chosen. This shot was filmed way back during the first season and also appeared in the episodes "Shadows of P'Jem", "Shockwave, Part II", "First Flight", and "Home".
- The episode introduces a potential predestination paradox into the overall Borg story arc. At the end of the episode, it is revealed that the assimilated Earth freighter dispatched a subspace message to the Delta Quadrant. T'Pol theorized it would take at least two hundred years for the message to reach the Delta Quadrant, implying that this may be how the Borg Collective originally learned of Humanity's existence (it is worth noting there is no evidence the signal was actually received). If the message was received, it may explain why, in the 24th century, the Borg specifically wanted Captain Jean-Luc Picard to speak for them and why they sent at least one vessel to the vicinity of Federation space, destroying several Romulan and Federation outposts in 2364, in the episode "The Neutral Zone". A series of incidents with the Federation followed over the next several years, culminating in the Battle of Sector 001, wherein a Borg sphere travelled to the 21st century in an effort to assimilate Humanity in the past, as seen in Star Trek: First Contact. The sphere was destroyed, and several drones from the vessel were frozen in an Arctic glacier in 2063, which were uncovered by the Arctic scientists 90 years later in "Regeneration", starting the causality loop all over again. It is also worth noting that if the signal which was sent by the Earth transport was not received by the Borg, then the Borg's first contact with the Federation and Humans would have been by way of assimilation of the USS Raven in 2356. If, however, the signal was received then the information in the transmission would have been 200 years out of date by the time the Borg received it.
- The ending of the episode is notably similar to that of the Star Trek: The Next Generation episode "Conspiracy", in which the crew of the USS Enterprise-D fight and destroy a hostile alien species, though not before said species managed to transmit a signal giving the location of Earth, and raising the fear that more of the aliens could invade again someday. Interestingly, the parasitic beings featured in that episode were originally intended to be agents of what would become the Borg, though no on-screen connection was ever suggested, due to it being dropped in light of budget constraints and the 1988 Writer's Strike.
- The episode has a much darker theme than other installments of Enterprise, reinforced by the music score composed by Brian Tyler. This is Tyler's second and last contribution to the second season, the first being "Canamar".
- The soundtrack "Star Trek: Enterprise Collection", released in 2014, featured five pieces from "Regeneration" on disc four – fan favorites:
- Borg Crash Site/Borg Awakening (3:13)
- Archer Tells Plan/Distress Call/Phlox Attacked (3:10)
- Hive Mind/Borg Hunt/Dead in the Water (6:43)
- Borg Attack/Borg Attack 2 (7:23)
- Message in a Bottle/Postponed (0:58)
- There was some controversy among fans over the fact that the Borg drones omitted their standard greeting ("We are the Borg") when they hailed Enterprise, conveniently keeping Starfleet in the dark about the identity of the cybernetic species. In their podcast commentary, the writers' justified this by pointing out that the Borg in TNG: "Q Who" never said "We are the Borg" when they encountered the Enterprise-D, nor did they use that catchphrase when they confronted Picard's ship again in "The Best of Both Worlds".
- According to Friedericy and Billingsley, many fans thought this episode "violated the timeline" and that it was a "jumping the shark" episode. Sussman mentioned that there were many concerns to bring back the Borg to Enterprise as it was the wrong era. ("Regeneration" audio commentaries, ENT Season 2 Blu-ray)
- Manny Coto cited this as one of two episodes, from the first two seasons of Star Trek: Enterprise, that he "especially enjoyed", the other such episode being "Cogenitor". (Star Trek Magazine issue 118, p. 25)
- The 2008 calendar Star Trek: Ships of the Line has the January cover by John Teska, titled "Things From Another World". This cover featured the crashed Borg sphere and the transport Arctic One from "Regeneration".
- On the broadcast of this episode on Channel 4 in the U.K. several scenes were edited including Phlox being injected by nanoprobes and his attempt at curing himself with radiation. (citation needed • edit)
- The events of this episode form the basis of the story for the 2006 game Star Trek: Legacy. A Vulcan scientist named T'Uerell is assigned to study the Borg debris and after learning their true nature, injects herself with Borg nanoprobes. Armed with knowledge of future events, she spends the next two centuries building her forces and waiting for the opportunity to seize control of the Borg Collective in order to use them to bring a state of total logic to the Alpha Quadrant.
- As part of ENT Season 2 DVD
- As part of Star Trek: Fan Collective - Borg
- As part of ENT Season 2 Blu-ray
- Star Trek: Enterprise Collection (soundtrack)
- Star Trek Monthly issue 105, 2003
- Star Trek Monthly issue 106, 2003
- Star Trek Monthly issue 108, 2003, set report by Penny Juday
- Star Trek Magazine issue 115, 2004
Links and references
- Scott Bakula as Captain Jonathan Archer
- John Billingsley as Doctor Phlox
- Jolene Blalock as Sub-Commander T'Pol
- Dominic Keating as Lieutenant Malcolm Reed
- Anthony Montgomery as Ensign Travis Mayweather
- Linda Park as Ensign Hoshi Sato
- Connor Trinneer as Commander Charles "Trip" Tucker III
- John Short as Drake
- Bonita Friedericy as Rooney
- Chris Wynne as Dr. Moninger
- Adam Harrington as Researcher
- Mark Chadwick as Male Tarkalean
- Paul Scott as Foster
- Adam Anello as Starfleet Headquarters crewman
- Brian Avery as Borg drone
- Jef Ayres as Haynem
- Craig Baxley, Jr. as operations division crewman
- Amy Kate Connolly as civilian
- Mark Correy as Alex
- Shawn Crowder as Borg drone
- Nikki Flux as command division crewman
- Peter Godoy as operations division crewman
- Glen Hambly as operations division ensign
- Peter Harmyk as Starfleet security officer
- Andy Keith as Borg drone
- Mark Major as Borg drone
- Eddie Matthews as operations division ensign
- Eric Norris as Borg drone
- Louis Ortiz as Borg drone
- Bobby Pappas as Starfleet Headquarters crewman
- Nicole Randall as Tarkalean female
- Pablo Soriano as Borg drone
- Warren Tabata as Starfleet security officer
- John Wan as operations division crewman
- Todd Wieland as operations division crewman
- Unknown performers
- Vince Deadrick, Jr. as
- Marty Murray as stunt double for Dominic Keating
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- "Regeneration" at StarTrek.com, the official Star Trek website
- "Regeneration" at Memory Beta, the wiki for licensed Star Trek works
- "Regeneration" at Wikipedia
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