Continuity mistake: In 1999, when everyone exits the lift, Tony and Killian stay inside the lift. As everyone leaves, Tony places his hand on the door frame. In the following close-ups of Tony and Killian, Tony's arm never shows any signs of moving his hand, but as he leaves the lift, his hand is no longer on the door frame. (00:02:35)
Continuity mistake: When Tony tells Killian to go to the roof, he leaves the lift. In this shot, there is a strand of Killian's hair layed over his face and nose in a straight line. In the next shot as he says "I'll see you up there", the bottom of the strand is suddenly curved over to the left side of his face. (00:02:40)
Continuity mistake: As Maya is showing Tony her research, in the shot where Tony says "Essentially, you're hacking into that of the genetic operating system...", Tony is shown to be looking at Maya. Then as he finishes off the sentence with "of a living organism" in the following shot, Tony is suddenly looking at the computer. (00:02:55)
Continuity mistake: Tony is in the bedroom with Maya Hansen, Happy is seen closing the sliding door. With the door just inches from being fully closed, a quick cut to Tony and Maya kissing, then back to Happy, and the door is almost fully open, with Happy in the process of closing it again just as the plant explodes. (00:03:45)
Continuity mistake: When Tony is in his garage injecting his arm, his chest piece is glowing brightly through his shirt, however, the very next shot when he is wiping his arm with the alcohol pad, his chest piece is suddenly turned off. (00:05:15)
Continuity mistake: When the Mark 42 is "done" assembling for the first time, in Tony's workshop, a digital model of the suit appears in the lower right corner of the screen. In this render, the suit is complete, but a moment later there is still one piece missing, which hits Tony so hard the entire suit falls apart. (00:07:30)
Continuity mistake: When Tony tests his mark 42, the HUD shot shows his mouth is bleeding, before the armor breaks that triggers his injury. (00:07:35)
Continuity mistake: After Tony hangs up on Happy using Face-Time, the scene cuts to Pepper and Killian having a conversation. As Pepper says "As in, enhanced soldiers, private armies, and Tony is...", she is cut off by Killian. When Killian starts speaking, he shifts his head to the left and starts looking downwards. In the next shot, he is suddenly looking straight back up at Pepper. (00:17:45)
Factual error: When Jon Favreau is in hospital, his IV bags are way too low. To be effective, the bags must be much higher so they can drip properly, even the one attached to the machine. (00:27:55)
Continuity mistake: Before Tony sends a holiday greeting to the Mandarin his car is pointed one way when he gets in, then the car faces the other direction. (00:28:45 - 00:29:45)
Continuity mistake: When Tony is giving his address to the Mandarin through the media the reporter in front of him has a cell phone which changes design between shots. (00:28:50)
Continuity mistake: When Tony is sending a holiday greeting to The Mandarin, he has sunglasses on. Then in the shot from behind, he doesn't have any glasses on. Then they reappear in the next shot and then he takes off the sunglasses. (00:28:55)
Continuity mistake: As the house is being attacked, Tony slides down the floor, smashes through a window and grabs onto the window frame. As the shot ends, his head is definitely under the frame, but in the instant shot following, his head is suddenly over the window frame. (00:36:00)
Continuity mistake: When Tony and Pepper are attacked by 3 missile-wielding helicopters, Tony, dressed in his metallic suit, has blood on his nose and cheeks. Problem is: The blood increases on his face, which is normal as it is still bleeding, but then it lessens. Then it gets worse again. (00:37:45 - 00:38:45)
Continuity mistake: When Jarvis wakes Tony up when he is in Tennessee, there is quite a lot of blood on his face. But when he takes off his mask, so before he had any time to wipe it off, the amount of blood decreases significantly. (00:39:50 - 00:40:30)
Character mistake: When Harley asks Tony what the light is coming from his chest, Tony responds "an electromagnet." Harley replies "What does it power?" An electromagnet is not a source of power. The arc reactor is the power source which powers both the electromagnet (to keep Tony safe from the shrapnel near his heart) and the Iron Man suit. (00:43:25)
Plot hole: How come the Extremis serum was able to regenerate Ellen Brandt's arm but not repair the scar on her face? According to the movie, the serum is supposed to rewrite the body's genetic code and constantly repair damaged cells, so her face should have been restored to its original state, just like her missing arm. Even if she had been born with the scar the serum would have healed it, just like it healed all of Aldrich Killian's physical impairments. (00:51:40)
Continuity mistake: When Ellen Brandt is confronting the Police Chief of Rose Hill, TN at the bar. The weapon that is visible that Brandt takes is a semi-automatic with a single stack magazine. The weapon which she shoots has a double stack magazine. (00:54:10)
Continuity mistake: When Stark gets trapped by the water tank he is completely soaked. When he walks back to the car with the boy he is completely dry and his hair is restyled with not enough time for this to happen. (00:56:50 - 00:57:55)
Factual error: In the scene in Tennessee, when Tony is being chased by the glowing "homeland security" lady. He throws a jug of oil and lights it on fire with the red hot handcuffs that he takes off. Then he somehow manages to slip a set of dog tags in a microwave and turns it on. This is to create a spark to explode the gas line that he pulls from the wall, which somehow isn't ignited by the large grease fire in the same room. (00:57:55)
Chosen answer: The Battle of New York was never specified to take place in 2012, we just know that the film came out then. Based on the newspaper we can assume that the battle was in June 2013, rather than some time in 2012 as many would have previously assumed.