Filmation rotoscoped three live action U.S.S. Enterprise shots from the original Star Trek (1966) series to use as stock animation. The shots rotoscoped were the ones where the Enterprise is coming toward camera in orbit (used in most of the original series), the shot where the camera zooms in on the top of the Enterprise (where the bridge is) seen in full on Star Trek: The Cage (1986) and a shot of the Enterprise zooming toward camera which also came from The Cage (1966) and was used rarely as stock footage.
Gene Roddenberry decided that this animated series was not "canon" (as the live-action series movies are) because he did the series for the money, and he would not have let the writers do some of things they did if he knew Star Trek would return in live-action. However, some of the writers of Star Trek: Enterprise (2001) strongly disagree with Roddenberry's opinion in this matter, and in Drawn to the Final Frontier (2006) they state that they regard this series as a legitimate continuation of the original Star Trek (1966) series. They point out, in those interviews, how they incorporated Trek Universe details from Star Trek: The Animated Series (1973) into the Enterprise prequel.
The life-support belts came about simply because the bulky spacesuits created for Star Trek (1966) were too complex to draw. (In the original series, the concept of the transporter had come about the same way: it got the crew to the planet without the expense of filming a landing sequence every week.) Ironically, the belts were never adapted for the later live-action movies and television series because making the actors "glow" via special effects would have cost more than making spacesuits.
When the animated series premiered on September 8, 1973, stations in Southern California ran a different first episode than that seen in the rest of the country: (Star Trek: The Animated Series: Yesteryear (1973). George Takei (Sulu) was running for a local political office, and area stations were afraid that running an episode (Star Trek: The Animated Series: Beyond the Farthest Star (1973)) in which Sulu appeared, would require them to give "equal" air time to Takei's opponents under the "fairness" doctrine then enforced by the FCC. Instead, they ran the Yesteryear episode because Sulu did not appear in that one.
According to Lou Scheimer there were never any ego problems between the cast members during recording sessions, although William Shatner and Leonard Nimoy had a tendency to count their characters lines and complain when one of them had too many more than the other.
The Enterprise included some minor and subtle differences and upgrades from the ship's live action appearances. According to Gene Roddenberry, this was in response to viewer feedback. For instance, the animated Enterprise showed two turbo lift doors on the bridge. Roddenberry said he was frequently asked what would happen if the turbo lift or it's doors malfunctioned, but he never had a proper answer. The addition of more alien crew members (notably Arex and M'Ress) was also a response to viewer requests, and Roddenberry joked that they had always wanted to feature more aliens, but that there were too few of then in the Screen Actors Guild. In reality, the animated format made it easier to depict more alien looking characters.
Because this animated series was deemed to be aimed at children, many of the darker elements in the scripts had to be excised, to the chagrin of Gene Roddenberry and other writers. This led to the "Star Trek lite" accusations against this series by disappointed fans of the live Star Trek (1966).
According to the book "Creating the Filmation Generation", Filmation was interested in producing an animated Star Trek series as early as 1969, just after the cancellation of the original series. However, the concept for this series was quite different, being aimed at a younger audience, The Enterprise crew would mentor a new training ship called the Excalibur and would train a group of teenagers. Each of the main Trek characters would have a young protégé, with names such as Steve, Bob, Stick, Chris, Tun-Tun, Stormy and Ploof. Filmation would subsequently use the rejected concept to develop the live action children's series Space Academy.
This was the first Saturday morning animated series by Filmation broadcast by NBC. The network had always refused to buy any cartoons by Filmation previously, but when Star Trek premiered Filmation finally had different shows on all three major networks on at the same time.
Sci-fi author Peter David later integrated the characters of M'Ress and Arex into his book series "Star Trek: New Frontier", starting with the novel "Gateways #5: Cold Wars". The two characters also appeared in DC Comics first volume Star Trek series, which for a time was written by David.