I think there's a lot, actually. The whole Appa being missing thing really didn't serve much purpose overall. They'll probably still include it in the movie, but it is fat that could be trimmed. Its only purpose in the long run is to give Zuko that moment where his actions conflict with his feelings, and for all we know that will be unfortunately simplified for American cinema. I think Book 2 stretched out a number of things for the sake of running a season, hence that one episode where they showed everyone going off and doing their own thing. It was down time when they reached the Earth Kingdom.
I also feel like the whole Earth Kingdom being secretly controlled by that one guy can be condensed quite a bit. The Fire Nation drill might also work better during the climax than where it occurred in the series. Television stories work differently than film. In TV you need to spread things out, whereas in a movie, more events happen at once. And no commercial breaks!
I also feel like the whole Earth Kingdom being secretly controlled by that one guy can be condensed quite a bit. The Fire Nation drill might also work better during the climax than where it occurred in the series. Television stories work differently than film. In TV you need to spread things out, whereas in a movie, more events happen at once. And no commercial breaks!