Character mistake: When young Tony Stark is telling his father that their helicopter's anti-flak chip didn't kick in, he acknowledges that it was his fault by saying he blew it. When his father corrects him and says "No Tony, we blew it. Stark and Son," Tony defensively says "The anti-flak chip failed, it's not my fault," completely contradicting what he said seconds earlier. (00:14:00)
Continuity mistake: When Nick Fury is overseeing the cleanup of Iron Man's attack on Firepower, the patch on his right shoulder is purple. When he is admonishing the soldier for playing around with Iron Man's helmet, the patch is now brown. A couple of shots later, the patch is now blue. (00:10:37)
Plot hole: When Mandarin is using his power rings to see the different kinds of suits that Iron Man has built, all the footage is clips of Iron Man using different suits in previous episodes. Assuming the rings had the power to do that, then they should also be able to show Mandarin that Iron Man is Tony Stark, because if they have the power to show Iron Man using different armors down to the most minute detail, then they should also be able to show him removing his armor to reveal Tony Stark underneath. Not to mention that H.O.M.E.R. frequently refers to Iron Man as "Mr. Stark" when communicating with him.
Continuity mistake: When the Mandarin is in the jewelry store at the end, he is shown as having only retrieved six of his ten power rings, with the ring in the jewelry store to be his seventh. In addition to previous episodes showing him to having already retrieved all ten rings, when he walks out of the jewelry store and places the ring he just stole on his left hand middle finger, you can see that he now has nine rings, with the thumb of his right hand being the only digit not adorned with a ring. (00:20:59)
Continuity mistake: When Hawkeye is saying "It's just you and me, Iron Man," the feathers on the right side of the arrows in his quiver briefly change color from white to yellow. Additionally, the head of the arrow nocked in his bow is spherical. When the shot changes, it is forked. (00:17:08)
Factual error: When Blacklash and Blizzard have hijacked the airplane, all the passengers are wearing their oxygen masks, indicating that the plane is at a high altitude. When Iron Man crashes through the window of the cockpit to take out Blizzard, there is no corresponding depressurization. (00:12:59 - 00:13:29)
Continuity mistake: When H.O.M.E.R. begins speaking to Iron Man during his fight with Crimson Dynamo, he is appearing on a monitor on Iron Man's right gauntlet. When Iron Man is then shown flying downwards towards Crimson Dynamo, the monitor is now gone. (00:02:02)
Other mistake: When Hulk throws the ring into the volcano, it is rapidly approaching the lava before Iron Man dives after it and successfully catches it before it lands in the lava. At the rate the ring was falling, it would have landed in the lava well before Iron Man could swoop down and catch it. (00:09:08)