* NightmareFuel: Heart's nightmare about his carnivorism. He dreams that he can hear his mom calling to him, but he can't find her. He then looks down to see that her calls are coming from ''inside his stomach''. He has ''eaten her and the rest of his family alive''. Understandably, he's pretty shaken when he wakes up.
* SomeAnvilsNeedToBeDropped: Carnivores need to eat meat, and this doesn't make them evil. Similar stories will often have the carnivorous family member miraculously manage to to live off of salads (or, in some more generous cases, bugs or fish). In this movie, while the art style doesn't indicate this, Heart is basically on the edge of starvation until he begins hunting. When [[spoiler: Heart's mother says that she would have offered herself as a meal to Heart if it came to that, Baku calls her out on her stupidity and points out that Heart would need more than just that single meal to live.]] Plenty of well-meaning human beings demonize carnivores while forgetting (or ignoring) the vital role they play in the natural order, which is where this particular message comes in.
* ViewerSpeciesConfusion: The purple carnivore attempting to eat Umasou is supposed to be the ''Chilantaisaurus'' from the book. Some viewers think it's a ''Carnotaurus'' due to its horns.
* TheWoobie: Heart.