Revealing mistake: There are obvious differences in the appearance of the "Ironman" and "War Machine" suits throughout the movie, as pertains to them showing a digitally-rendered suit vs an actual physical suit that the actor/stuntmen wear. Whenever a real suit is shown on an actor, it is quite bulky, most noticeably around the abdomen/stomach areas, and the size of the head-piece.The digital versions are much slimmer in the abdomen areas and the headpieces are much smaller and more compact.
Revealing mistake: Just after the scene where Tony meets Justin Hammer, Tony is looking at himself in the bathroom mirror and the supposed 'mirror' Tony raises his hand to suck on his bleeding finger. However, we can see the back of the also supposed 'real' Tony, he also raises his hand as the camera zooms into the mirror, but his hand movement is much later than the hand movement of the 'mirror' Tony. Therefore proving that both Tony's are two completely different actors so when zooming in, the camera could create the illusion of a mirror without the camera filming itself. (00:28:40)Professor Lazarus
Revealing mistake: In the scene where the Senator is presenting the awards at the end of the movie, one of the microphones (third from the left) on the podium does not have a cable plugged in, which can also be seen in the next shot. In the proceeding close up shot, the mistake cannot be seen. In the very final shot before the credits roll, the same mistake can be seen. (01:56:10 - 01:57:00)