(written from a Production point of view)
The Enterprise travels back in time to 1968, where the crew encounters the mysterious Gary Seven who claims to be sent by advanced beings trying to help Earth. (Season finale)
- "Captain's log. Using the light-speed breakaway factor, the Enterprise has moved back through time to the 20th century. We are now in extended orbit around Earth, using our ship's deflector shields to remain unobserved. Our mission – historical research. We are monitoring Earth communications to find out how our planet survived desperate problems in the year 1968."
After Captain Kirk finishes his log entry, suddenly the Enterprise is rocked, and Spock reports that they appear to have intercepted someone's transporter beam. Kirk remarks that there were no such devices in the 20th century. Spock maintains that someone is beaming aboard. Spock discovers that the transporter beam originates more than a thousand light years away. Scott finds that difficult to believe, stating that no transporter beam could reach that far, not even in their time. Suddenly a man in a dark suit, holding a black cat, appears on the transporter pad.
The strange man asks Kirk why he was intercepted and who his interceptors are. Kirk identifies himself and tells the man that he is aboard the United Space Ship Enterprise. The man asks what planet they are from, and Kirk says they are from Earth. This the man refuses to believe, because 20th century technology would not allow for a ship like the Enterprise. But when he notices that Spock is a Vulcan, he realizes the ship is indeed from the future and asks to be beamed down to Earth. As security arrives, the man identifies himself as Gary Seven, calling himself a man from the 20th century, and gives his cat's name as Isis. Kirk states, however, that Humans of the 20th century do not go beaming around the universe. Seven explains that he has been on another planet, one much more advanced, and that he was beaming to Earth from that planet when the Enterprise intercepted him. When Kirk asks which planet it is, Seven says that the inhabitants wish their planet to be kept secret and that even in Kirk's time, it will remain unknown. Seven reiterates that he is of this time period and adds that, if Kirk does not allow him to do what he needs to do down on Earth, then Kirk will have changed history. But Kirk, unsure that Seven is telling the truth, decides to keep him aboard the ship until that can be determined. However, Seven tries to escape, overpowering the security guards, and he even shrugs off Spock's attempt at a Vulcan neck pinch. Seven is only subdued by a phaser stun from Kirk. Kirk calls Dr. McCoy and asks him to examine the mysterious man in the brig to determine if he really is Human.
- "Captain's log, supplemental. A man in a 20th century business suit – what is he? Not even Spock's Vulcan neck pinch could stop him. Without our phasers, he would have overpowered all five of us. I find it difficult to believe the mysterious Mr. Seven can be Human. And yet, suppose he is."
In the briefing room, Spock, who is stroking Isis, mentions that he finds himself strangely drawn to the cat. Ensign Chekov reports that analyzing the direction Seven's transporter beam came from show no habitable planets in that area of the galaxy and Scott says that they will not be able to analyze the transporter beam, as it had fused their recording circuits. The beam could have brought him across tremendous distances across space, and perhaps even through time; there is, quite simply, no way to know. Spock also mentions that current crises on Earth could fill a tape bank, noting that, on this one day alone: "There will be an important assassination today, an equally dangerous government coup in Asia, and, this could be highly critical, the launching of an orbital nuclear warhead platform by the United States, countering a similar launch by other powers." Kirk and Spock briefly discuss the nuclear arms race and how that once the sky was filled with orbiting H-bombs, the slightest mistake could have brought one down, setting off a nuclear holocaust.
Back in the briefing room, McCoy tells Kirk that Seven is indeed Human, but also that his is a totally perfect body, without a physical flaw at all within him. This raises the possibility that he could be an alien taking Human form, and Spock points out again that Seven could be telling the truth. Kirk laments that neither of them is telling him anything definite. At that point, Isis jumps out of Spock's lap and leaves the briefing room. Security then alerts them that Seven has escaped. In the transporter room, where Isis rejoins him, Seven renders Lemli and Leslie unconscious with his servo and beams down before Kirk can stop him.
Seven materializes inside a transporter chamber, disguised as a vault concealed behind a sliding rack of drinking glasses, in what appears to be an otherwise normal office.
Seven accesses a computer behind the bookcase. Seven asks for the locations of agents 201 and 347. The computer asks Seven to identify himself and Seven tells the computer to check his voice pattern, and it will identify him as Supervisor 194, code name Gary Seven. The computer recognizes his voice pattern but is unaware of a Gary Seven being assigned to this planet. Seven then tells the computer that he is a Class One supervisor and that the computer is to override all previous instructions and answer his questions. The computer identifies itself as a Beta 5 computer capable of analytical decision and forces Seven to prove himself by describing the mission of the two agents that were sent here. Finally Seven, after griping that he has "little love for Beta 5 snobbery," relents and tells the computer that missing agents 201 and 347 are a male and a female descendant, respectively, of Humans taken from the Earth approximately six thousand years ago (circa 4000 BC) and that they were specially engineered and trained for this mission. The problem is that on Earth, its science and technology have progressed faster than its political and social knowledge have. Their mission is to prevent Earth from destroying itself before it can become a peaceful society. The computer states that Seven's information, while incomplete, will suffice and tells Seven that the agents have not reported for three days. Seven tells the computer to immediately begin a search and begins describing how to do so when the computer tells him it is aware of proper search procedures.
Meanwhile, back aboard the Enterprise, Kirk, Spock, and Scott are trying to determine where Seven had beamed down. Scott says that they can get to within approximately one thousand meters of where he had gone. Spock reminds Kirk that following him down is very risky because they may end up accidentally doing something to alter history. Kirk says he knows but he must also know if Seven is being truthful with them. Kirk tells Scott to have ship's stores prepare the proper costumes and then prepare to beam them down.
In his apartment, Seven learns that the agents' mission was to disable a rocket that will launch an American orbiting nuclear platform which is a counter-move to an opposing country that has already done the same. This appalls Seven, who says that this arms race is the same kind of nonsense which almost resulted in the destruction of planet Omicron IV, which the Beta 5 computer confirms. Seven asks if the warhead has been disabled, but the computer says both that it has not been and that there are just under ninety minutes before launch. Seven says that unless the agents are immediately located, he will have to undertake their mission in their absence.
Having beamed down, Kirk surreptitiously calls Scott with his communicator and tells him to lead them to Seven. Scott gives Kirk the coordinates and Kirk and Spock proceed.
The computer provides Seven with various pieces of false identification, including identification listing Seven as a colonel with the CIA, a lieutenant in the NYPD, and a colonel with the NSA. It also produces a map of McKinley Rocket Base. At that moment, a young woman walks in and asks if anyone is in. Seven steps out and demands to know where she has been. The woman sees no reason to tell him and asks who he is. Seven asks where 347 is but she neither knows nor understands, jokingly replying that perhaps he is with 348. She then threatens to call the police. After insisting that she sit down, Seven, wrongly believing her to be agent 201, tells her that he is "Supervisor 194, code name Gary Seven" and that he needs a complete report of all that she has done in the last three days. As the woman prepares to start typing, Seven flips a switch and tells her not to bother with her hands. When she wonders how she will type, the typewriter begins typing everything she says. This gets the young woman very frustrated, and after she yells at the typewriter to stop typing what she says, Seven finally switches it off and she says that she will quit. Seven then realizes that she is not acting. Using his servo, he locks the door; he then accesses the computer and has it identify the woman in the room. The Beta 5 identifies her as Roberta Lincoln and says that she is a secretary hired by Agents 347 and 201. Realizing the terrible mistake he has made, Seven asks Roberta what work her employers said they were doing and she says they were doing research for a new encyclopedia. Seven tells her she can go, though she will not be helping her country, unless of course, she does not care for her country. When Roberta protests that she does, Seven tells her that thanks to his incompetence, he has made her aware of some top secret devices vital to the security of the nation. He shows her his false CIA ID and she accepts that it is legitimate. Isis opens the door and meows at Seven. Seven explains to Roberta that Isis is a trained cat and asks Roberta not to let anyone in and she agrees to do so.
Out on the street, Kirk calls Scott again, and Scott tells Kirk that the source was about thirty meters higher than his present location. Thus, Kirk and Spock enter Seven's apartment building.
The Beta 5 tells Seven that agents 201 and 347 were killed in an automobile accident ten miles north of McKinley Rocket Base on Highway 949. Seven laments the uselessness of dying in such a manner and asks if the facts are verified. The computer does confirm this, noting that the description of the agent's bodies is accurate.
On the floor outside Seven's apartment, Scott tells Kirk which way to go and they find the right apartment. Kirk rings the doorbell and Seven has the computer deactivated. Roberta opens the door, but when Kirk asks about Seven, she says that she has no idea who he is talking about, that this is a government office, and that they should leave immediately. But Kirk will have none of it, demanding to know where Seven is. Roberta demands that Kirk leave, but he refuses, and she finally grabs the phone and calls for the police. Kirk and Roberta briefly struggle over the phone and she asks Seven to come help her. Seven, meanwhile, has entered the transporter in his safe and disappeared. Spock discovers where Seven was, and Kirk goes in and has Spock restrain Roberta. She manages to pull Spock's cap off and is dumbstruck at the sight of Spock's pointed Vulcan ears.
Seven rematerializes inside the rocket base and observes the rocket which is armed with the warhead.
Kirk finds Seven's map of McKinley Rocket Base. Roberta tells them she has already called the police to the office. When the police arrive, Spock tries to keep Roberta quiet, but she screams before he can. Kirk calls Scott, whom he orders to perform a wide scan, as they will be moving, and be ready to beam them up. They run into the office, but Roberta runs to the door, admits the police, and points them into the office. They run in just as Kirk orders them beamed up – and the two police officers are beamed up with Kirk and Spock, all four disappearing before Roberta's eyes. Kirk and Spock jump off the transporter platform, and Kirk immediately orders Scott to beam the policemen back down, which he does. The two policemen are returned to the office, leaving them dumbstruck at what they have seen and experienced and Roberta not knowing what to believe.
At the rocket base, there are only fifty minutes until launch. Seven is approached by a security guard as he approaches launch control. The guard, Sergeant Lipton, has Seven lower Isis to the ground and requests identification, and Seven produces his CIA ID. While the guard calls to verify, Isis distracts Lipton, allowing Seven to stun him with his servo and he then takes the phone and tells the security identification office at the other end that everything is now OK. He then sits the stunned guard down and tells him to take a nap. Seven then makes his way to the gantry elevator by hiding in the trunk of the launch director's, Cromwell's, car. When the car arrives at the launch pad, he exits the trunk, hides in the elevator, reaches a gantry, removes an access panel with his servo and begins to rewire the rocket.
Meanwhile, Kirk, Spock, and Scott, in the transporter room, search for Seven at the launch site by reflecting their sensors off a low-orbiting weather satellite. Unable to find him, Kirk and Spock decide to beam down to the base to search for Seven the old-fashioned way. They materialize in front of the previously stunned guard as he awakens. Lipton takes them into custody and escorts them to the control room in the launch complex. They are briefly interrogated, but all attention is focused on the launch preparations. Kirk and Spock stand there unable to act.
Meanwhile, planning to quit again and telling the computer interface that she promises not to tell anyone about Seven or anything she has seen, Roberta accidentally discovers that depressing a pen holder on the desk opens the sliding glass rack. She then fiddles with the combination lock to the safe and succeeds in opening the safe/alien transporter room. At the same time, using the ship's sensors, Scott locates Seven on the rocket gantry while he is manipulating wires on the rocket. Scott calls for security and then attempts to beam Seven back aboard. Sensing the transporter beam, Seven gathers Isis into his arms. But at the same time, Lincoln's fiddling with the safe/alien transporter controls pulls him back to the NYC office.
In the launch facility, Kirk and Spock watch helplessly as the countdown progresses. The security officers inspect Kirk's and Spock's phasers and communicators. The security supervisor tells Kirk that only the slightest possible charges will be brought against them if they explain why they are here and what they are doing. Kirk can only stand silently and watch as the rocket launches up toward space.
- "Captain's log, supplemental. Spock and I are in custody. Even if we'd talk, they wouldn't believe us. We're powerless to stop Mr. Seven or prevent the launch, or even be certain if we should. I have never felt so helpless."
In the office, Seven is initially angry at Roberta for interfering, but he then calms down when he realizes that what she had done likely kept him from being transported back aboard the Enterprise and again taken prisoner. He then goes over and begins to work at the Beta 5 computer. He inquires whether he had done enough to take control of the rocket, and the Beta 5 confirms that he had.
Seven uses the Beta 5 exceiver circuits to cause the third stage of the American rocket to malfunction and veer off course. He also arms the warhead and Roberta, who had become very suspicious of Seven, hits him on the head with a small jewelry box, for she now realizes that what he has been doing is beyond the CIA's abilities. She grabs Seven's servo and tells him to stay where he is. Seven begs Roberta to let him finish what he had started, otherwise when the rocket warhead detonates somewhere in six minutes, it will start World War III.
From the science station on the bridge, Chekov and Sulu see the warhead arm and call Scott in the transporter room to inform him of what has happened. Sulu tells Scott that the computers indicate an impact somewhere in the heart of the Eurasian landmass. Uhura, listening in to broadcasts from her station in multiple Earth languages, reports that she is receiving military alerts from the major powers. Scott decides that he will have to risk calling Kirk, and tells Uhura to open a channel to his communicator.
At launch control, the mission planners note the malfunction in the rocket and try to override it and get it back on course. When the warhead arms itself, the scientists are confused as to how it could have done so on its own. They prepare to send a self-destruct signal to prevent the H-bomb from otherwise detonating on an unsuspecting population somewhere.
Kirk, taking advantage of this distraction, steps over and tries to activate his communicator, but Lipton catches him and sends him back to his corner. Just then, Scott attempts to contact Kirk for instructions. When the communicator beeps and the rocket base guard picks it up and tries to talk to Scott, Spock steps over, under the guise of showing Lipton how to use it, and uses his nerve pinch to render him unconscious again. Kirk has Scott beam them directly to Seven's office. Unfortunately for the scientists, the self-destruct signal does not work. The lead flight controller picks up a red phone to make a call to the President.
Back in Seven's apartment, Seven tries to tell Roberta the truth about what has been happening and that truly advanced civilizations would neither take strange forms nor visit Earth in force, explaining that the best option is to bring Humans to their planet and train them for generations, until they are needed on Earth. Roberta tells him that she wants to believe him, for she knows that her world needs help; this explains the seemingly insane conduct of some of the people of her generation, of whom she points out, "We wonder if we're gonna be alive when we're thirty."
Just as Seven tries to run back to the computer, Kirk and Spock enter the apartment again. Kirk asks Spock if he can detonate the warhead using the computer, to which Spock replies that he can attempt it. Seven says that he wants the warhead detonated too, but that he will have to do it, and at least a hundred miles above the ground, so that it will frighten the people of Earth out of the arms race. At that moment, Scott calls Kirk, telling him that the Enterprise's monitors show all major powers on full missile alert and a retaliatory strike is ordered upon warhead impact. Spock says that without more time, he can only estimate, and Seven angrily asks Kirk to allow him to do his job. Kirk insists that he still does not know what Seven's job is, and that for all he and Spock know, Seven may set the controls so that the warhead may not even be detonated. Then Roberta points the servo at Kirk and demands that he leave Seven alone. Seven quickly grabs it from her hand and tells her that the servo was set to kill. He deactivates it and then hands it over to Kirk. Kirk tells Spock if he cannot detonate the warhead, then they will both have to trust Seven. Spock tells Kirk that in the absence of facts, there is no logical decision and that he will have to rely on his Human intuition to guide him.
After a brief moment, Kirk tells Seven, "Go!" Seven runs over to the Beta 5 and begins working the controls, activating a visual of low Earth orbit and having the computer count down the miles by tens. Finally, at 104 miles, Seven manages to detonate the warhead.
Later in the day, Seven is dictating the last bit of his report into the typewriter. "…and in spite of the accidental interference with history by the Earth ship from the future, the mission was completed." Spock then corrects Seven and tells him that by all appearances they did not interfere but that, rather, that the Enterprise was simply part of what was supposed to happen on this day in 1968. Kirk says that their record tapes show that while it was never generally revealed, a malfunctioning sub-orbital warhead was exploded exactly 104 miles above the Earth. Spock adds that, furthermore, it caused the nuclear powers to re-assess the risks of a nuclear orbiting platform. That everything turned out just how it was supposed to leaves Seven feeling relieved.
For a moment, Roberta looks over at Isis and sees a rather gorgeous woman. She steps over to Seven and asks if he will explain who that is. Seven says that it is simply his cat. When Roberta looks back, Isis is a cat again. Seven then asks Kirk what else their record tapes show, but Kirk says they cannot, in turn, reveal all they know. Spock does say that it would be safe to say that Seven and Roberta have some interesting experiences ahead of them and Kirk agrees with that assessment. Kirk calls to be beamed up by Scotty, Spock tells Seven to "live long and prosper," and Kirk says that the same goes for Roberta. They beam back aboard, and the Enterprise leaves orbit to go back to its proper time.
"Humans of the twentieth century do not go beaming around the galaxy, Mister Seven."
- - Kirk, after Gary Seven beams aboard the Enterprise
"It's impossible to hide a whole planet."
"Impossible for you, not for them."
- - Scott and Seven, on the Assigners' planet
"Mr. Spock, historical report."
"Current Earth crises would fill a tape bank, captain."
- - Kirk and Spock
- - Seven and Roberta Lincoln, as they meet for the first time
"Well, how do you expect me to type? With my nose?"
- - Lincoln, after Seven sets up the typewriter
"I'm telling you, you're through monkeying around with my country's rocket."
- - Lincoln to Seven, after the warhead rocket separates
"I know this world needs help. That's why some of my generation are kind of crazy and rebels, you know? We wonder if we're gonna be alive when we're thirty."
- - Lincoln, as she doubts Seven's story
"Without facts, the decision cannot be made logically. You must rely on your Human intuition."
- - Spock to Kirk, as the warhead descends to Earth
"That, Miss Lincoln, is simply my cat."
- - Seven, after Lincoln sees Isis in Human form
Original pilot (no Star Trek connection)
- Story outline "Seven" by Gene Roddenberry: 20 April 1965
- Revised story outlines: 23 April 1965, 25 April 1965
- First draft teleplay: 14 November 1966
- Revised first draft: 16 November 1966
Star Trek version
- Story outline by Roddenberry and Art Wallace: 21 October 1967
- Revised story outline by Wallace: 13 November 1967
- First draft teleplay: 21 November 1967
- Revised first draft: 11 December 1967
- Second draft teleplay: 14 December 1967
- Revised second draft: 18 December 1967
- Revised draft by Roddenberry: 20 December 1967
- Final draft teleplay by Roddenberry: 1 January 1968
- Additional page revisions: 3 January 1968, 5 January 1968, 9 January 1968
- Filmed: 2 January 1968 – 10 January 1968
- Day 1 – 2 January 1968, Tuesday – Desilu Stage 9: Int. Engineering, Sickbay, Bridge, Transporter room
- Day 2 – 3 January 1968, Wednesday – Paramount Stage 5: Int. Gary Seven's apartment, Hallway corridor
- Day 3 – 4 January 1968, Thursday – Paramount Stage 5: Int. Gary Seven's apartment
- Day 4 – 5 January 1968, Friday – Paramount Stage 5: Int. Gary Seven's apartment
- Day 5 – 8 January 1968, Monday – Paramount Windsor Street backlot: Ext. New York City street, Paramount officer buldings: Ext. McKinley Rocket Base
- Day 6 – 9 January 1968, Tuesday – Desilu Stage 10: Int. Mission control room; Desilu Stage 9: Int. Briefing room, Transporter room
- Day 7 – 10 January 1968, Wednesday – Desilu Stage 9: Int. Bridge, Briefing room, Transporter room; Desilu Stage 10: Int. Rocket Platform
- Original airdate: 29 March 1968
- Rerun airdate: 9 August 1968
- First UK airdate: 4 November 1970
- This episode was designed partly as a pilot for a new series featuring Gary Seven and his mission. Star Trek was teetering on the brink of cancellation late in its second year, and Roddenberry hoped to get a new show going for the fall season. The first draft pilot script (14 November 1966) had no mention of Star Trek or its characters. 
- Assignment: Earth did not enter production as a television series, but Seven and Roberta were featured in several stories and they spun-off a comic book series from IDW Publishing, Star Trek: Assignment: Earth by John Byrne.
- The plot concept of benevolent aliens secretively helping Earthlings, as opposed to the much more common "villain aliens" scenarios, was later resurrected by Roddenberry for his movie The Questor Tapes.
- Stock footage of the Enterprise orbiting Earth (without clouds) is reused from "Miri".
- A closeup of Montgomery Scott behind the transporter station is recycled from "The Enemy Within".
- According to The Star Trek Compendium (1st ed., p. 140), the first draft script (dated 20 December 1967) had the Enterprise bridge crew watching an episode of Bonanza on the viewscreen.
- The establishing shot of downtown Manhattan used to open act 2 is also seen in numerous episodes of The Man from U.N.C.L.E. throughout that series.
- The typewriter is a Royal Emperor, which could type from a cassette tape recording of the text.
- The Beta 5 computer contains many components from the M-5 multitronic unit in "The Ultimate Computer". These components were recycled yet again for "All Our Yesterdays" and "Spock's Brain".
- A new effect is used for the transporter as Seven is beamed aboard for the first time – slow motion flames can be seen behind the opaque back wall of the chamber. This may be due to the Enterprise's unintentional interception of Seven's unusually powerful transporter beam.
- The rocket storage buildings at the rocket base were studio buildings on the Paramount lot, with NASA footage of Apollo rockets matted in above them. This is the third and last episode utilizing Paramount office building exteriors for location filming, after "Bread and Circuses" and "Patterns of Force". Launch Director Cromwell's car matches the car seen in one of the stock footage sequences.
- NASA shot all their footage using the anamorphic format, hence all the rocket launch stock footage in this episode is cropped from the 2.35:1 aspect ratio to television's conventional 1.33:1. 
- The rocket stock footage in this episode is actually of three Saturn Vs: footage of the rocket on the ground is a combination of the SA-500F Test Vehicle (the only Saturn V to feature "USA" markings on the third stage) and Apollo 6 (the only Saturn V launched with a white service module). Footage of the rocket launching is of Apollo 4.
- This is the only episode of the second season to have Gene Roddenberry credited as "Producer" instead of "Executive Producer," the first time he had received such a credit since the first season. Roddenberry wanted to be very "hands-on" for this episode, as he hoped to turn it into a spin-off series. He rewrote Art Wallace's script and was heavily involved in production, including sets, props, casting of actors, and even the costume of Terri Garr – he insisted on shortening her mini-skirt to be "more revealing," much to the anger of costume designer William Ware Theiss. (Inside Star Trek: The Real Story) Garr had a very unpleasant time filming this episode, perhaps stemming from Gene Roddenberry's involvement in decisions regarding her costume, specifically the length of her skirt. The hem was taken up so much it became very distorted. In interviews since, she has refused to talk about Star Trek in any way. 
- This is also the only episode of the second season that has no credited studio executive in charge of its production, as Herbert F. Solow had left Paramount Television by this time, and would be replaced by Douglas S. Cramer beginning with the third season.
- Robert Lansing (Gary Seven) is the only Star Trek: The Original Series guest star whose credit appears after the opening credits instead of during the end credits – complete with character name. The fact that the episode was to serve as the pilot for a proposed spin-off series explains the unique credits.
- William Blackburn appears as a rocket control room technician in this episode, one of the few times he is seen out of a Starfleet uniform. He can also be seen walking in front of Gary Seven just after he materializes at McKinley Rocket Base.
- This episode marks the final appearance of the unknown actor who portrayed Bobby. His appearance in the corridor was "new" recycled footage that was originally shot during the filming of "The Corbomite Maneuver".
- This is the only episode of Star Trek in which time travel is treated as "routine." The Temporal Prime Directive does not yet appear to have been proposed, let alone taken effect.
- This is the only episode where a Federation transporter system is used to intercept and re-direct another transporter beam.
- Along with the Vians and Khan, Colonel Gary Seven is one of the few humanoids to have ever manifested insensitivity to a Vulcan nerve pinch.
- This episode was first aired on 29 March 1968. Six days later, on 4 April 1968, there was indeed an important assassination – that of Martin Luther King, Jr..
- However, the coincidence goes beyond this: Spock says that the same day as the assassination that the US was launching an orbital nuclear warhead platform. The King assassination was the same day as the launch of the unmanned Apollo 6 Saturn V rocket. This same Saturn V amazingly enough also suffered a serious mishap and went off course. The details of the mishap with the Saturn V on April 4th differ greatly in detail from the events of Assignment: Earth. However, Kirk comments at the end of the episode that the real events were never "generally revealed" at the time. It makes sense therefore to assume, within the context of Star Trek's fictional history that there was a massive cover-up about the Apollo 6 mishap and that a false cover story was put out to hide the truth that they were launching a nuclear weapon into orbit. This episode uses footage of the Apollo 4 Saturn V, the only previous test of that rocket. Chronologically, the closest candidate to Spock's other "prediction" of a government coup in Asia would be the July 17th military coup in Iraq that brought Saddam Hussein to power (17 July Revolution).
- This episode takes place entirely in 1968, with no scenes in the 23rd century. Along with ENT: "Storm Front" (which takes place in 1944), this is one of only two Star Trek episodes based entirely in the 20th century. Furthermore, both episodes take place mostly in and around New York City.
- The events of this episode, which take place in 1968, occurred (from the point of view of the Enterprise crew) over a year after those of "Tomorrow is Yesterday", which take place in 1969.
- In various novels and comics, the alien race that trained Gary Seven was revealed as an ancient race called the Aegis.
- Seven and Lincoln have appeared in several Star Trek novels (Assignment: Eternity and the two-volume series, The Eugenics Wars: The Rise and Fall of Khan Noonien Singh by Greg Cox) and short stories ("The Aliens Are Coming!" by Dayton Ward in Strange New Worlds III, "Seven and Seven" by Kevin Hosey in Strange New Worlds VI and "Assignment: One" by Kevin Lauderdale in Strange New Worlds VIII).
- Gary Seven has also appeared in several comic books, including "The Peacekeeper Part One", "The Peacekeeper Part Two: The Conclusion", "Split Infinities", "Future Imperiled", and the Star Trek: Assignment: Earth mini-series.
- The Department of Temporal Investigations novel Forgotten History explicitly places the episode on April 4, 1968.
Video and DVD releases
- Original US Betamax release: 1986
- UK VHS release (two-episode tapes, CIC Video): Volume 29, catalog number VHR 2381, 3 September 1990
- US VHS release: 15 April 1994
- UK re-release (three-episode tapes, CIC Video): Volume 2.9, 22 August 1997
- Original US DVD release (single-disc): Volume 28, 10 July 2001
- As part of the TOS Season 2 DVD collection
Links and references
- Terri Garr as Roberta Lincoln
- James Doohan as Montgomery Scott
- George Takei as Sulu
- Nichelle Nichols as Uhura
- Walter Koenig as Chekov
- Don Keefer as Cromwell
- Lincoln Demyan as Sergeant
- Morgan Jones as Col. Nesvig
- Bruce Mars as First Policeman
- Ted Gehring as Second Policeman
- Paul Baxley as Security Chief
- James Doohan as Mission Control announcer (voice)
- Barbara Babcock as
- William Blackburn as
- Frank da Vinci as Brent
- Rudy Doucette as rocket base technician
- Eddie Paskey as Leslie
- Roger Holloway as Roger Lemli
- Jeannie Malone as
- Edwin Rochelle as Passerby #1
- Robert C. Johnson as Ground Control (voice) 
- Sambo and two unknown cats as Isis in cat form 
- April Tatro as Isis in Human form
- NASA stock footage used for
- Unknown actors as
- William Blackburn as the stand-in for DeForest Kelley
- Frank da Vinci as the stand-in for Leonard Nimoy
- Jeannie Malone as the stand-in for Teri Garr
- Eddie Paskey as the stand-in for William Shatner
- Edwin Rochelle as the stand-in for Robert Lansing
6,000 years before; 20th century; 1948; 1968; 1978; acceleration; accident; agent (government agent); Agent 201; Agent 347; alien; all decks alert; "all right"; altitude; analysis; ancestor; animal; apartment; arc; area; arms race; Asia; assassination; automobile accident; auxiliary transmitter; baby carriage; balance of power; behavior; Bermuda; Beta 5 computer; bird; birthmark; body; "Bones"; briefing room; business suit; button; Canary Islands; cat; Central Intelligence Agency (aka CIA); century; chance; channel; charge; chronological age; circuit; civilization; class 1 supervisor; close orbit; coat rack; code name; colonel; control center; control setting; costume; countdown; country (aka nation); coup; course; crisis; custody; date; day; deflector shields; degree; Department of Investigation; descendant; destruct signal; detonation; device; dial; Dodge Coronet; doll; door; Earth; Earth Cold War; East 68th Street; elevator; employer; encyclopedia; engineering personnel; era; estimate; Euro-Asian continent; exceiver (aka exceiver circuit); existence; experience; expert; extended orbit; fact; Federal Bureau of Investigation (FBI); feet; finger; flight control; flight path (aka trajectory); flight telemetry; force shield; Ford Falcon; Franklin; French language; friend; fur coat; Gary Seven's homeworld; gantry (aka rocket gantry); gantry area; generation; government; government office; green; groovy; ground station; Ground Station 3; Ground Station 4; Ground Station 11; guard dog; H-bomb; hair; hand; heart; hello; Highway 949; historical report; historical research; history; Hobson, Albert; Homicide Squad; honey blonde; hour; Human; Human history; hundred; hydrogen; idea; identification; identification card; impact; inch; incompetence; information; inspection; "in store for them"; instruction; intelligence quotient; international agreement; intruder; Intruder alert; "in the first place"; intuition; IQ; jealousy; jerk; job; knowledge; Johnson, Lyndon B.; launch; launch area (aka launch pad or launch site); launch director; launch site scan; light-speed breakaway factor; light year; Liquid hydrogen; location; logic; machine; major power; malfunction; McKinley Rocket Base; medical analysis; meow; meter; mile; military alert; Milky Way Galaxy; minute; missile; missile alert; mission; mistake; mole; name; nap; National Security Agency; navigation report; news broadcast; New York City; New York City Police Department; nonsense; no parking sign; north; nose; nuclear holocaust; nuclear warhead; "oh, my gosh"; Omicron IV; "on the double"; "on the one hand...on the other hand"; orbit; orbital nuclear warhead platform; oxygen; phaser; plan; Plymouth Belvedere; Plymouth Satellite; Plymouth Savoy; phone; planet; police; pound; Precinct 19; Precinct 81; President of the United States; prisoner; problem; product; profession; programming; progress; proof; pound; question; range safety; rebel; recording circuit; record tape; research; retaliatory strike; report; risk; rocket; rocket stage; rule; Ryan, John; safety group; Saturn V; science; science personnel; search; search procedure; second; secretary; security alert; security confinement; sensor; sensor scan; sergeant; servo; ship's store; shoulder; sleep; smoking; society; South Africa; "stand by"; star; star map; status board; sub-orbit; suborbital platform (aka orbital platform); subway; Supervisor 194; supervisory personnel; tape bank; technology; telemetry control transmitter system; telephone; thing; time; time period; time travel; tracking station; transporter; transporter beam; transporter circuit; transporter room; training; truth; typewriter; typing; United States of America; USS; verification; visual scan; voice pattern; Volkswagen Beetle; Vulcan; Vulcan nerve pinch; Vulcan salute; "wait a minute"; warhead; weapon; weather satellite; World War III; worry; year; "your lucky day"
- "Assignment: Earth" at StarTrek.com, the official Star Trek website
- "Assignment: Earth" at Memory Beta, the wiki for licensed Star Trek works
- "Assignment: Earth" at Wikipedia
- "Assignment: Earth" at MissionLogPodcast.com, a Roddenberry Star Trek podcast
- "Assignment: Earth" • Gary Seven, Isis, & Roberta Lincoln at AssignmentEarth.ca – includes the series' proposal, and first script along with its first and final Star Trek scripts
|Previous episode produced:
"The Omega Glory"
|Star Trek: The Original Series
|Next episode produced:|
"Spectre of the Gun"
|Previous episode aired:
"Bread and Circuses"
|Next episode aired:|
|Previous remastered episode aired:
|TOS Remastered||Next remastered episode aired:|