This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Space Beasts
The Death of the Humanimals of Nuthanger Farm. That is all.
When Ichabod kills a Lizard Man in the five episode pilot when he falls in with the Wranglers, doubles as a Tear Jerker when he realizes Humanimals are people. Before he ran away and joined the Wranglers he was somewhat ungrateful for all the nice things the Fellowship crew did for to try and help him feel better, when he realizes the Wranglers are pure evil, he realizes how ungrateful he was and how much the Humanimals did for him.
In the Escape from Alderbaren Arc when Ichabod is infiltrating Castle Vortex as a new recruit, Marzipan is framed for flushing a cherry bomb down the toilet. Marzipan is innocent but she can't offer an explanation for why the toilets blew up, before something really ugly can happen, Ichabod volunteers to 'punish' her. Punishment in this case always means something sexual. In a very short time, Ichabod explains to Marzipan, he loves her and doesn't want to hurt her, but he has to do something or else his cover will be blown. Ichabod knows Marzipan has lasted for seven years in captivity without losing her virginity, he offers her the compromise of 'forcing' her to give him a blow job. Marzipan knows that tomorrow she will be free, so she decides a few minutes of a bad taste in her mouth is better then death. So she gives Ichabod a blow job...with all the soldiers watching! That has got to be one of the most humiliating ordeals either Ichabod or Marzipan ever went through, It doesn't help that after he comes, and Marzipan runs away retching that Ichabod is congratulated by the soldiers, claiming he is now 'one of them'.
During the Paradise 5 Mini-Arc Bill, Jim, Bob, Ichabod and Edward are kidnapped, Bill, Jim and Bob are sent to the Gladiator Games While Ichabod and Edward are sent to strip clubs. While we do worry about Edward we're more worried about Ichabod who at this point of the story is only 15 years old. Torture Technician and Crocodile Man Pocho informs Ichabod he is expected to sing bawdy songs and Strip for the patrons. Ichabod initially refuses but then Pocho informs Ichabod if he doesn't perform his three friends will die in the arena! (Fortunately, Marzipan, Jordan and Samantha get him out of there before he has the strip but still it's heart wrenching)
Humanimal/Human crossbreeding seems to be fraught with potential hazards, Kate reveals that the reason mixed couples are often Human Boy/Humanimal Girl not vice versa is the fact many male Humanimals' genitalia are simply just to much for human female to handle and this just after we're told that Bill's night of drunken sex ended with the teenage girl Maddy dying after having sex with Bill. Bill has never forgotten that night and has felt horribly guilty ever since, this is probably the biggest deconstruction of Bigger is Better in Bed you'll see in Furry Fandom Work.
We don't have many opportunities to observe day-to-day Wrangler society, but it is obvious that they go through slaves at an enormous rate. Animal life on their planets is constantly used to make humanimals as fast as they can be bred or faster-when the Wranglers should be able to use their advanced technology to clone animal life in huge numbers or genetically engineer them to breed many times more quickly than natural. If they ever settle on an earth-like planet (Or one colonized by an advance terraforming force before it is civilized), this would result in billions of humanimals being killed over a few generations. Across the length and breadth of the [Empire], the scale of the genocide could be unimaginable, especially over the last 6000 years of its existence.
What happens when you feed an animal, say, a wildebeest, into the 'Evolution Machine' that makes humanimals, and they've got an intestinal parasite such as those common in untreated water world-wide? Does the Crystal distinguish between the organisms and only anthropomorphize the mammal, or do you instead get two humanimals intertwined, one trapped inside the other but now much closer to human size, writhing and twitching until they finally die?