Well, for one the movie seems to neglect the entire conflict in ender and replace it with the desire to please an aging harrison ford and look possibly cool in the process. Also, the whole other side of the book, Val's and Peter's story seem to be omitted as well. I doubt they'll put in Bean, at least not as he is in the book, that'd be too much feels for an action flick.
Edit: Besides, they are going to leave out all the things that would make the audience think (Can't have someone perk up and think during a movie! What a ridiculous idea!), so no "Remember, the enemies gate is down!"