Hilarious in Hindsight: One episode has Tantor state that "they ought to put warning labels on [scary books]". Nowadays, certain books do have parental advisory stickers, and even ESRB-style breakdowns of objectionable content.
Ho Yay: Max, the journalist in "Tarzan and One Punch Mullargan", is really in awe of Tarzan, with some of his comments sounding like he's got a crush on the ape-man.
Magnificent Bastard: Renard Dumont, the smart, cunning and greedy businessman. He shamelessly cheats his clients to make a quick buck, and remains charming while doing so.
When Tarzan and Professor Porter try to stop Professor Philander from caging (and he plans on killing too) the silver ape Mangani, he cuts a rope Tarzan was hanging on, sending him falling several stories to his apparent death. Rather than let Archimedes examine and try to save his son in law, Philander plans on stranding him at sea and tossing Tarzan's body overboard.
Lt. Colonel Staquait crossed it by ordering Hugo and Hooft to burn a village full of mostly innocent women and children. AND then he became obsessed with having them executed for daring to object to this atrocity calling them deserters despite the fact that they had a damn good reason to be.
Nightmare Fuel: Some of the villains can be really scary. La and her leopardmen, Tublat, Mabaya the rogue elephant and Hista the giant python all get their nightmare-evoking moments.
Dania from "Tarzan and the Rift". In that episode, Tantor gets the chance to ask Dania out on a date, but the evening gets ruined by Terk showing up, making noise with household items, and being oblivious to the other characters' feelings. At that point, Dania being alienated by Terk is justifiable. To make matters worse, this is all just a big misunderstanding. The whole conflict could've been avoided if Terk had just apologized to Dania for making such a bad first impression, or at least done something nice to make up for it. But instead, the episode acts like Terk's actions were automatically forgivable. The episode never acknowledges the misunderstanding and expects us to dislike Dania for believing that Tantor should stop hanging around with Terk, despite the fact that her belief is based on Terk making a bad first impression and doing nothing to make up for it.
On the other hand, she meant well the whole time, untill she thought she would lose a friend. Dania simply said he had to choose between his best animal friend and her, while she could have said "wherever we go don't let her anywhere close from me !".
Philander at the end of "Tarzan and the Missing Link". This is mostly because of all the protagonists taking a level in jerkass by being unnecessarily harsh to Philander. Also, Philander only brought those two men to Africa because they were threatening his life. Porter should've at least been respectful while rejecting Philander's offer at the end, instead of literally roaring in his face. However, Porter's attitude becomes more forgivable if you saw "Tarzan and the Silver Ape" before this episode, where Philander crossed the Moral Event Horizon by almost throwing Tarzan to his death, so Porter is understandably fed up with his antics.