The writers of the animated series used, essentially, the same writers' guide that was used for the live-action Star Trek: The Original Series. A copy of the "series bible", as revised for TAS, is held in the science fiction research collection at the Samuel Paley Library, Temple University, Philadelphia.
While the freedom of animation afforded large alien landscapes and believable non-humanoid aliens, budget constraints were a major concern and the animation quality was generally only fair, with very liberal use of stock shots (as was often the case with many of Filmation's shows). There were also occasional mistakes, such as characters appearing on screen who were elsewhere, or a character supposed to appear on the bridge's main viewing screen, but then appeared in front, indicating bad ordering of animation plates. These were typically isolated errors however. Occasionally, though, parts of episodes would be animated at a near-theatrical quality level.
Initially, Filmation was only going to use the voices of William Shatner, Leonard Nimoy, DeForest Kelley, James Doohan and Majel Barrett. Doohan and Barrett would also perform the voices of Sulu and Uhura. Leonard Nimoy refused to sign up to lend his voice to the series unless Nichelle Nichols and George Takei were added to the cast — claiming that Sulu and Uhura were of importance as they were proof of the ethnic diversity of the 23rd century and should not be recast.
Koenig was not forgotten, and later wrote an episode of the series, becoming the first Star Trek actor to write a Star Trek story. Koenig wrote "The Infinite Vulcan", which had plot elements of the original Star Trek episode "Space Seed" blended into it.
As is usual for animation, the voice actors did not perform together but recorded their parts separately to avoid clashing with other commitments. For instance, William Shatner, who was touring in a play at the time, would record his lines in whatever city he happened to be in and have the tapes shipped to the studio. Doohan and Barrett, besides providing the voices of their Original Series characters and newcomers Arex and M'Ress, performed virtually all of the "guest star" characters in the series, except for a few notable exceptions such as Sarek, Cyrano Jones and Harcourt Fenton Mudd, who were performed by their original actors from The Original Series. Occasional other guest voice actors were also used, such as Ed Bishop (Commander Straker on UFO) who voiced the Megan Prosecutor in "Magicks of Megas-Tu", and Ted Knight (Ted Baxter on The Mary Tyler Moore Show) who voiced Carter Winston in "The Survivor".
The 22 episodes of TAS were spread out over two brief seasons, with copious reruns of each episode. Most are directed by Hal Sutherland.
All the episodes of this series were novelized by Alan Dean Foster and released in 10 volumes under the Star Trek Logs banner. Initially, Foster adapted three episodes per book, but later editions saw the half-hour scripts expanded into full novel-length stories.
Star Trek: The Animated Series was the only "Star Trek" series to not feature a cold open ("teaser") and started directly with the title sequence (although some overseas versions of the original live action series, such as that run by the BBC in the UK in the 1960s and 70s, ran the credits before the teaser).
The writing in the series benefited from a Writers Guild of America, East strike in 1973, which did not apply to animation. A few episodes are especially notable due to contributions from well-known science fiction authors:
Filmation later went on to produce the hit He-Man and the Masters of the Universe (1983-85), which occasionally used modified character and set designs from Star Trek: The Animated Series, mostly as background material. (He-Man and the Masters of the Universe also had several Trek-similar stories, most notably "The Arena", which is very similar to Star Trek: The Original Series's first season episode, "Arena"). Later series also shared many of the stock sound effects from both Star Trek: The Animated Series and Star Trek: The Original Series. Filmation also recycled some of the background music for Star Trek: The Animated Series in their later shows Shazam!, Tarzan and the Super 7 and Sport Billy. (Some of the music had already been reused from the previous season's Brady Kids and the Treasure Island feature, and were shared with that season's Lassie's Rescue Rangers).
In addition, a few facts introduced in the animated series have been referenced in the live-action productions:
The episode "The Lorelei Signal" provides a rare instance in early Star Trek in which a female took (temporary) command of a starship. Due to the incapacitation of the male members of the crew, Uhura assumes command of the U.S.S. Enterprise from Scotty. Other instances occurred on the very first and very last adventures ever filmed of the original series:
"The Lorelei Signal" and "The Infinite Vulcan", the latter written by Walter Koenig, are rare occurrences where Captain Kirk comes close to actually saying, "Beam me up, Scotty" (long erroneously believed to be a Star Trek catchphrase), when he commands "Beam us up, Scotty." Star Trek IV: The Voyage Home arguably comes closer to it by having Kirk say "Scotty, beam me up".
The Star Trek Chronology by production staffers Michael Okuda and Denise Okuda does not include the animated series, but does include certain events from "Yesteryear". The timeline in Voyages of the Imagination dates the events of the series to 2269-2270, assuming the events of the show represented the final part of Kirk's five-year mission, and using revised Alan Dean Foster stardates.
Since Roddenberry's death in 1991 and the consequent firing of Richard H. Arnold (who vetted the licensed tie-ins for Roddenberry's "Star Trek Office" at Paramount during its latter years), there have been various references to the animated series in the various live-action series. In the Star Trek: Deep Space Nine episode "Once More Unto the Breach", Kor referred to his ship, the Klothos, which was first named in the TAS episode "The Time Trap". Other DS9 episodes to reference the animated series include "Broken Link", where Elim Garak mentions Edosian orchids (Arex is an Edosian) and "Tears of the Prophets" where a Miranda class starship is called the USS ShirKahr (sic) after Shikahr, the city from "Yesteryear". David Gerrold, who contributed two stories to TAS, stated in an interview his views on the canon issue:
Writer-produer D.C. Fontana discussed the TAS Canon issue in 2007:
More DS9 references to the animated series include the episode "Prophet Motive" where the title of healer is resurrected from "Yesteryear" as well. Vulcan's Forge is also mentioned in "Change of Heart", where Worf wants himself and Jadzia Dax to honeymoon there.
The Star Trek: Enterprise episodes "The Catwalk" and "The Forge" included references to "Yesteryear", the latter featuring a CGI rendition of a wild sehlat. The remastered Original Series episode, "Amok Time" featured Shikahr in the background as Spock beams up at the episode's end.
In recent years, references to the Animated Series have also cropped up again in the licensed books and comics. M'Ress and Arex, characters from the animated series, appear in the Star Trek: New Frontier novels by Peter David, in which M'Ress and Arex are transported through time to the 24th Century, and are made officers on board the U.S.S. Trident. (David's previous use of these characters, in TOS movie-era comics published by DC Comics, had been prevented by Gene Roddenberry's office.)
A race introduced in the episode "The Jihad", represented by M/3/Green, is named the Nasat in the Starfleet Corps of Engineers e-book novellas. These stories feature a regular Nasat character, P8 Blue. The Vulcan city of ShiKahr also appears in many books. Paula Block of CBS Consumer Products is responsible for approving proposals and all completed manuscripts for the licensed media tie-ins, and has granted many such uses of TAS material since Roddenberry's passing.
Amarillo Design Bureau, Inc. has — as part of its license for the Star Fleet Universe series of games — incorporated many aspects of the Animated Series into its works, not least being the inclusion of the Kzinti, although in a modified form. In addition FASA used elements from the animated series in its sourcebooks and modules for its Star Trek role-playing game.
Star Trek: Enterprise producer Manny Coto has commented that had that show been renewed for a fifth season, the Kzinti would have been introduced. Starship designs were produced which closely resemble the Kzinti/Mirak ships from the Star Fleet Universe, a gaming universe that includes the boardgame Star Fleet Battles and its PC analogue Star Fleet Command.
The animated series was, according to the Nielsen ratings, not popular enough with young children. According to series' producers it was intended to be enjoyed by the entire family. Although the accuracy of the ratings system conducted by the ACNielsen company has been vehemently disputed by its supporters and detractors since their first implementation, these results have been cited by fans and critics as justification for the show's brief run of only 22 episodes. However, in the 70s, very few animated series went beyond a few seasons as it was usually more profitable to start a new series. The series did receive critical acclaim and a Daytime Emmy award, the first such award for the franchise. According to both Roddenberry and an NBC press release, this was the justification for six additional episodes being ordered by the network for the series' second season.