There's a rumor going around that Iron Man 3 has hit a major creative snag. According to Roger Wardell, who frequently leaks Marvel Studios info on his Twitter account, the movie is undergoing a massive, last-minute rewrite:
But sources close to Marvel tell io9 that this story is bunk — there were no outside writers brought in, and no major rewrites. There was some rewriting on set, as usually happens during this sort of production, but nothing beyond the usual sort of stuff that makes particular scenes or sequences work better. So no need to panic about Iron Man 3, people!