Other mistake: When Aang is reading the letter from The Guru, as Sokka says, "What's a guru? Some kind of poisonous blowfish?" his right eye loses its white colour three times during the shot. (00:18:19)
Other mistake: When the group goes to hug Sokka before he and Aang go to Chameleon Bay, you can briefly see that Toph is incorrectly drawn with arrow tattoos on her hands, like Aang has. This happens very fast, but you can still catch it when watching the episode normally without pausing or slowing it down. (00:20:35)
Chosen answer: When Sozin says "So I wiped out the Air Temples," we are indeed seeing the three mountains of the Eastern Air Temple burning, with the two bridges being gone in this shot (S3-E6). This does conflict a bit with the image we see of the Eastern Air Temple, with the two bridges intact, when Aang and Appa fly to that Air Temple seeking Guru Pathik (S2-E19). This may possibly be considered a mistake, but the fact is that when we are seeing the burning of the Eastern Air Temple it's from the point of view of Zuko, who is merely reading from Sozin's autobiographical account, and envisioning everything he's reading, which in his mind includes the bridges having been destroyed.
Super Grover ★