(at around 53 mins) When Tony asks Natasha how she might celebrate her last birthday, the sound of Natasha's heels clacking against the floor are heard as she walks away, despite there being carpet under her feet.
(at around 1h 3 mins) When Nick Fury and Natalie Rushman are with Tony Stark and give him a vaccination to cure his blood from poisoning him, Nick Fury gives him a syringe filled with what he says is "Lithium Dioxide". However, lithium ions have a single positive charge while oxygen ions have a double negative charge. As such, lithium oxides have two atoms of lithium per atom of oxygen, not two atoms of oxygen per lithium as "Lithium Dioxide" would suggest. In addition, any oxide of lithium would decompose immediately in any kind of water solution, such as would be required to inject it into a person.
(at around 1h 11 mins) While showing off the M134 minigun, Justin Hammer claims the military refers to is as "Puff the Magic Dragon". The title was actually given to the AC-47 gunships that used the minigun.
(at around 1h 3 mins) When Colonel Fury confronts Tony, Natasha says "According to Mr Stark's database security guidelines, there are redundancies to prevent unauthorized usage". In reality, redundancies do not help prevent unauthorized usage. They provide fall-backs.
(at around 1h 11 mins) When Hammer is showing Rhodes an array of weapons for sale, in addition to incorrectly calling an M26 Modular Accessory Shotgun System an M24 shotgun, he also states that it is a pump-action, when it is actually a straight-pull bolt-action.
(at around 1 min) At the end of Iron Man when Tony Stark reveals that he is Iron Man, he has blue index cards in his hand. At the beginning of Iron Man 2 when Anton Vanko is watching the news when Tony reveals, he doesn't have the cards in his hand like in the first movie.
(at around 1h 2 mins) While Tony Stark is talking to Nick Fury in the diner, the poisoning streaks switch sides of his neck. Most of the time they are on Tony's right, but in one shot, they are on Tony's left.
(at around 8 mins) During the Expo speech Stark is wearing a pinstripe suit with a white shirt and black bow tie. When he is checking his blood toxicity immediately after the speech he is wearing a different suit, black shirt, and no tie.
(at around 55 mins) During Tony's birthday party, when one of the girls starts "pulling" bottles, a brunette in the background wearing a bikini is shown wearing a towel in one shot, then without the towel covering her legs in the next.
(at around 36 mins) When Whiplash has just been disarmed, after attacking Tony Stark at the racetrack, in one shot he is on his back, looking up, and blood runs down the right side of his mouth all the way to the base of his ear. Then when the angle changes to show the CRS taking him away, the blood is gone.
(at around 1h 26 mins) When the particle beam from Iron man's particle accelerator is cutting everything in half, it doesn't cut the cables going to the center piece holding the material that the new element will be created from, and it doesn't damage the center piece either. It also doesn't damage the particle accelerator itself, which is highly improbable considering that it could clearly cut through steel.
(at around 36 mins) When Whiplash (Mickey Rourke) attacks Tony Stark at the racetrack, after Tony puts the portable Iron Man suit on, Whiplash wraps his left-hand whip around Tony's right arm, and his right-hand whip around his throat. Eventually he detaches the left-hand whip, and pumps additional electricity through the right-hand one, electrocuting Tony. When the shot changes to a close-up of Whiplash's, he is clearly holding his left arm forward, not his right. When it returns to a longer shot, he's using his right hand again.
(at around 1h 21 mins) When Tony arrives to his mansion and is about to create the wire frame copy of the expo, he first blows the dust off it. This is after racing back in his car with the top down and the expo panels standing up in the passenger seat. In light of Tony's driving style, there should be no dust left on the panels.
(at around 44 mins) Ivan meets Hammer in the airplane hanger. When the guards take off Ivan's cuffs he doesn't have anything in his mouth, then the camera cuts away and cuts back to Ivan, he suddenly has a toothpick in his mouth.
(at around 35 mins) When Happy is using the car to keep Ivan Vanko away from Tony Stark at the raceway, the camera changes from close up of the driver to exterior of the car. Most of the close ups show Happy putting the car in drive, even when the car is shown going in reverse.
(at around 1h 28 mins) When Justin Hammer locks up Ivan Vanko with the "babysitters" he is wearing a black jacket which unzippers with every cut. In the final cut to Vanko, the jacket is completely zippered up again.
(at around 7 mins) When Tony Stark is on stage at the Stark Expo, he is visibly walking forward in several close-up shots. In every long-shot, however, he is shown standing in the very center of the round part of the stage.
(at around 10 mins) When the U.S. Marshal hands the subpoena to Stark, she is holding it in her right hand as she faces the camera. In the immediate reverse shot (focusing on Stark at the wheel), she is holding the subpoena in her left hand.
(at around 1h 20 mins) When Tony is alone in Pepper's office with his belongings, after he throws the strawberries in the trash, he is shown facing Pepper's desk and looking to his right. In the next shot, he appears facing the door looking to his left.
(at around 1h 15 mins) When Tony Stark is watching the 8mm film footage of his dad that was provided by Nick Fury, he is visibly sitting in the projector's path when the camera is facing him. In the reverse shot's, there is no reflection of this on the screen (no shadows).
(at around 1h 40 mins) Natalie Rushman proceeds to take out a security guard, who is about to pepper spray her, by wrapping her legs around his neck. All of the shots prior to him being slammed to the ground show a tanned man. In the shot where he is slammed to the ground, the guard has changed to a pale-skinned man no longer holding the pepper spray.
(at around 1h 20 mins) When Tony Stark is left alone in Pepper's office to retrieve his personal items, the main door is left closed but slowly opens as if the door latch did not engage. However, as the next camera angle has Tony staring at the large model of the city of the future, in the background the main door is completely closed.
(at around 1h 37 mins) As the attack at the Expo starts all the phones are dead, all the cells are blocked as is said explicitly. Pepper comes in and calls the police on her cell phone as it cuts to Happy Hogan and again explicitly stated that none of the phones are working.
(at around 7 mins) After the 'Ironettes' finish their performance, Tony Stark walks onto the stage. When he looks at the Ironettes the camera is facing his front, and his bow tie is crooked. The camera angle changes to show his back, and when he turns around to see his front, his bow tie is straight.
(at around 32 mins) When the Rolls Royce is outside the Hôtel de Paris, the Louis Vuitton shop is seen one door down the street. However when the car peels out leaving the hotel, the Louis Vuitton store is much farther away and there are two additional stores between it and the hotel entrance.
The video footage of the Press conference where Tony revealed he was Iron Man was not the same footage seen in Iron Man (2008). Tony was holding blue cue cards when he said he was Iron Man. In this footage, he was not.
At the beginning of Ironman 2, he lands in the super suit at Stark Expo, he of course has the prominent arc reactor right in the middle of his chest. Moments later he removes the Ironman suit with the aid of robots, revealing a full tuxedo. The arc reactor is under the tuxedo.
(at around 2h) In the film credits for the theatrical version, the song "Highway to Hell" incorrectly lists Brian Johnson as co-writer. Angus Young, Malcolm Young and Bon Scott are the correct writers (fixed on home video release)
LTC Rhodes is wearing a class ring from the United States Air Force Academy on the middle finger of his left hand. These rings are worn on the ring finger in keeping with the policy that used to restrict the amount of jewelery a serviceman could wear. Graduates of the service academies, who were bachelors while cadets or midshipmen, were loathe to discard their class rings upon marriage so most sport a custom made wedding band flush against the class ring next to the knuckle.
(at around 14 mins) When LTC Rhodes is testifying before the Senate Committee, he is wearing a dress uniform with Gold Oak Leaf Clusters on his epilets. LTC Oak Leaf Clusters are Silver, the Gold Oak Leafs indicate the rank of Major.
The striped sign on Vanko's workshop is a DOT placard placed on trucks. It indicates that the truck is carrying environmentally hazardous liquids (DOT 3082). Doors in buildings are marked with four-part NFPA hazard labels.
Ivan Vanko's mustache changes in size and lip coverage several times. This is easily explained by the fact that there was a long period of time spent developing his own arc reactor. He could have shaved multiple times during this period.
Ivan Venko's goal in his first attack was to show that Iron Man could be harmed, but his plan required several events to happen for which he had no control. 1. Stark had to be at the race or at least close enough to respond to what Venko was doing on the track. 2. If Stark was at the race, he would need to have access to his Iron Man suit 3. If Stark was at the track suited up, he would need to be close enough that Iron Man would not simply destroy Whiplash from a distance with the many various range weapons on the suit.
The crux of the movie is Tony Stark searching for a replacement to palladium in his chest piece, which is poisoning him. Rhodey's iron man armor runs from an arc reactor not implanted in his chest. Tony could have removed his arc reactor and replaced it with a nontoxic battery at any time without ceasing to be Iron Man.
(at around 1h 1 min) After Rhody lands at Edwards Air Force Base, in the wide shot both the B2 Stealth Bomber and War Machine have disappeared. This is because the Air Force wouldn't let them film the aircraft from that angle, and War Machine was eliminated to save production costs.
(at around 40 mins) Pepper Potts sees a full intra day chart of Stark Industries stock on TV at 7:30 AM Pacific (10:30 AM Eastern). The NYSE opens at 9:30 AM Eastern, so it has been open for only a hour.
(at around 1h 30 mins) Tony clearly hits Mute when he's on the phone to Ivan so he can talk to JARVIS without Ivan knowing. He never touches the screen again to un-mute when he starts talking to Ivan again.
The goof items below may give away important plot points.
(at around 1h 55 mins) At the end when Senator Stern presents the medals to Tony Stark and Rhodey, Tony Stark puts his arm behind the Senator's back for the photo, but in the next shot of the cameraman running towards them to take a photo it is in front of him again.
(at around 1h 35 mins) AIR Drone #303 is the first to go "offline" by being destroyed by the ARMY Drones. Later, a drone explodes after it hits the column under the highway but the computer screen shows AIR drone 305 already offline and AIR Drone 303 going offline.