Continuity mistake: In the scene where Mickey Rourke is in the laboratory discussing how long it will take him to reproduce the robots, his glasses change position from him wearing them to not wearing them throughout the conversation.
Continuity mistake: When Ivan climbs the ladder to inspect the Hammer prototype, his hair changes repeatedly from underneath the frames of his glasses to outside the frames.
Continuity mistake: The scene in the Monaco lounge when Tony Stark and Justin Hammer are sitting down at a table with Christine Everhart to give an interview, Hammer sets his drink on the table while he's standing but then the shot immediately cuts to him sitting down with the drink still in his hand.
Continuity mistake: Before Hammer starts eating dessert (and thus much before the "moving spoon and cherry" continuity mistakes), there's a back angle where he dips his spoon into the dessert and starts eating. The angle cuts to a front view with the spoon laying spotless on the saucer, and Hammer saying "I'll start with dessert", and then repeating the whole previous scene as if it were the first time.
Continuity mistake: In the beginning when Tony's press conference is on TV in Anton Vanko's home, the dialogue exchange between Tony and Christine Everheart has more talking than that same scene in "Iron Man" at the end. In "2", Christine mentions that Tony hates body guards in the exchange, but, this is never said in the first "Iron Man".
Continuity mistake: After the core is removed from Whiplash during the race scene, a stream of blood visibly trails from the corner of his mouth. The shot changes to him spitting and the blood is gone. The shot changes again and it reappears.