The Characters

The Herd

Rider and Horse are both orphans.
Glendale is wanted by the Moletaurs for more than just theft.
Durpleton actually is 47 like he claims; All of the members of the Herd (minus Horse) are roughly middle-aged, with Zulius being the eldest of the bunch (though he probably doesn't want anyone knowing exactly how old he is).
Zulius and Splendib's original rivalry was based around the drama between Taylor Swift and Katy Perry, which also happened to involve backup dancers.
Stabby did start to accept Centaurworld even before his transformation, such as with the scene where he regrets hailing the Nowhere King in "My Tummy, Your Hurts".

Mysterious Woman

The Woman was unaware of the General being connected to the Elktaur until she had found the Elk chained up in the dungeon.
The Woman was very intrigued by Centaurworld, and when she was younger, she would travel there and learn magic (possibly from the Shamans). Her hair being purple represents a bit of Centaurworld's magic becoming a part of her.
- Her transformation was never completed because her toxic relationship with the Elktaur introduced a trauma that halted the process midway and that she wasn't able to recover from for a long while.
The Mysterious Woman did indeed kill off the Elktaur at the end.

General/Elk/Elktaur/Nowhere King

The General and the Elk have the same mind/personality; the team wanted to showcase how someone changes when they have privilege vs. when they don't.
The General has a different voice actor to showcase how he changed from his original self when he split in the Rift.
The Elktaur kept going to food memories because it's a mental safe space for him that he escapes to, to avoid his trauma.
"Last Lullaby" was meant to show empathy for the Nowhere King/Elktaur, but he was killed off because his problems don't excuse his actions (lying, genocide, gaslighting the Woman)
- Likewise, he would've continued killing if the Woman hadn't intervened and killed him off to end the cycle of abuse.

Others

The birdtaurs don't like Wammawink due to them not being privy to her backstory, and what they did see of her made them think her as being overbearing.
The "tweets" are, in fact, newborn birdtaurs. The ones that make it to adulthood get to join the rest of the birdtaurs.

The Worlds

All centaurs possess some form of magic. The shamans simply specialize in magic.
There are very few older/elderly humans in the Human World because it's almost exclusively the younger generation (such as Rider) that survived.
One doesn't change based on the style of the world they're in, they change based on how much they let the world change them. The reason that Horse and Stabby changed the way they did was because the former had learned to adapt to Centaurworld (even if she didn't want to) while the latter had a sudden realization.
- This is also the reason why the Elktaur and the Mysterious Woman don't look as cartoony as everyone else in Centaurworld. The former didn't spend much time in the Human World, but the time he did spend really affected him. In the latter's case, while she was trapped in Centaurworld for quite a while, she didn't let it affect her in any way except for changing her hair color, which she had acquired when she was younger and travelling to and from Centaurworld.
The war had lasted for hundreds of years.

The tiny versions of the centaurs all have memories of being the original full-sized centaur, and from their point of view remember making tiny versions then suddenly “waking up” as one. They can also create even smaller microscopic versions of themselves.
Megan had imagined Comfortable Doug as being pansexual, but she didn't want to comment too much on the characters' sexualities because she wanted the audience to draw their own conclusions.
The Mysterious Woman and the General/Nowhere King are all stuck in a vicious cycle due to the magic between them. As a result, they had all barely aged since the Rift had first closed a while ago.
The song “Who is She” is about both Horse and Rider, particularly the part when Horse says "she's worth it". It's for her as well.
If Megan could do new stories for Centaurworld, she would like to explore how the Herd moves on since the main events of the series. However, she doesn't think she'll be able to for reasons unexplained.