What are some cases of "early installment weirdness" in Avatar?

Early on in the show Appa was often called a "flying bison" but as the series goes on this name disappears and he's referred to as a "sky bison."

Book 1 was looser when it came to background characters wearing clothing that was color-coded on the nation they were from.

Also in book two, there is a big deal about Aang's affections for Katara conflicting with his ability to go into the Avatar State, but this never really comes up again and we do see past Avatars in relationships and being just fine.