Germans Love David Hasselhoff: It was much more successful in Britain than at home (although it took until the '90s for the series to get a network screening - in its initial run and repeats thereafter it was shown in every ITV region except STV (Scottish Television, in Central Scotland); Channel Four gave it its first UK-wide airing in the mid-90s, and both the series and the Compilation Movies regularly turn up on cable TV).
Hell Is That Noise: In the TV series, hoofbeats, as that can only mean that gorilla soldiers are approaching.
They Just Didn't Care: The TV series was determined to exemplify this trope. We see ape surgeons wearing surgical masks, which indicates that they understand modern germ theory...except that, in "The Cure," they suddenly don't. Again, we see an ape wearing spectacles, so they must have some basic knowledge about glass-making, optics and lens grinding. Well, until Galen has suddenly never seen glass or heard of a magnifier. They've got advanced metal-working skills, but have never heard of fish nets. The list goes on.
Partially explainable by the Schizo Tech invoked due to the Science Is Bad beliefs of the orang-outangs — for example, in "The Surgeon" (the above-mentioned episode featuring surgeons in surgical masks), the apes haven't identified basic blood types and Galen is able to fake being a doctor by seriously discussing the medicinal qualities of bleeding patients with leeches. Plus, "apeworld" is provincial; out in the boonies, things are a lot simpler, while closer to Capital City technology tends to be higher.
Fridge Brilliance: In the TV series, the origin of the Ape civilisation is that they evolved full sapience after humanity destroyed itself and took over. While they purposefully eradicated the true history, it's quite logical that they stole as much human-knowledge as they could to build their own empire. Add the orang-outang conspiracy to keep the true history of the world hidden from the apes, and, naturally, much of their technology falls under Monkey See, Monkey Do — they're imitating human knowledge as best they can without knowing or understanding why something is done. Ape doctors wear germ masks because they're, without knowing it, aping human doctors — they don't know that the masks prevent infection, they just know that "this is the way it's done".
Also, it should be noted that in "The Surgeon" the time we saw the apes wearing masks was a surgery arranged by our heroes, who had knowledge of surgical masks, and were using a human medical text. In addition, when a surgeon from the hospital wanted to join them Galen had to ask if he minded wearing a mask to which he claimed he "found very useful in protecting us from the vapours". So it would seem that normally ape surgeons didn't wear masks.
Values Dissonance: In-universe example in the TV series. In "The Gladiators," Burke refuses to kill Tolar after he defeats him in the ring. Tolar is furious.