Animation Age Ghetto: A continuation of the live-action Star Trek: The Original Series, with Gene Roddenberry at the helm, scripts by many of the same writers, and the original cast (except Walter Koenig) providing voicework. The show takes itself just as seriously as the original, with no concessions to its possibly younger audience. Stories included an episode about religious intolerance titled "Jihad", and another in which Nurse Chapel gets a whiff of Harry Mudd's love drug and tries to jump Spock's bones (or at least as close to it as TV would allow back then). It was well received enough to earn the franchise's first Emmy Award. This is remarkable when one considers that the company that made it, Filmation, to at least some extent actively encouraged the Animation Age Ghetto, as they felt it their civic duty to act as agents of social uplift for the kids, and not to scare or puzzle them too much. And yet, it aired in the 1970s on Saturday morning—anything not kid-friendly in those slots was literally forbidden back then.
Continuity Lock-Out: Several episodes of the animated series call back to or serve as continuations of episodes from the original 1967 live-action series, so it would be wise to watch at least the majority of The Original Series before viewing this series.
Narm: Sometimes the limited number of voice actors could make things a little silly, as in "The Lorelei Signal," when Nichelle Nichols and Majel Barrett have to voice, like, seven different people.
For some reason, there's a shot of Kirk's face being too close to the screen several times an episode. (Was this Shatner's idea?)
To be fair, other characters get awkward closeups too, so it's more likely Filmation realized that filling the screen with someone's face needs less animating than the Enterprise's machinery.
Suspiciously Similar Song: Filmation was unable to use the original theme song, so the opening theme for the animated series was a new song that almost sounded like, as The Agony Booth put it, "the TOS theme played sideways".
Uncanny Valley: Lt. M'Ress looks unintentionally unsettling when she is viewed up close, especially when her eyes are wide open. Not helped by the show's Limited Animation.