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.
In a scene where 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.
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.
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.
In the scene where 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.
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.
In the beginning of the movie, 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 so you can see his back, and when he turns around to see his front, his bow tie is straight.
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 you can see the main door is completely closed.
When Happy is using the car to keep Ivan Vanko away from Tony Stark at the raceway you can see 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.
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.
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.
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.
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.
Before Stark uses the particle accelerator to power the new core, we see it cut through the wall and various objects. However, none of the cables attached to the core are severed, even though they were in the path of the beam.
During the Stark Expo Opening Ceremony Tony Stark is clearly wearing a white shirt with black tie, but only seconds after walking offstage (while he's checking his blood toxicity) he's wearing a black shirt.
During the scene in which 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.
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 1:38:55 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.
When Whiplash jolts Iron Man during their first encounter at the race track, he's using the whip in his right hand. When the scene switches immediately to a a close-up of Whiplash, he's using the whip in his left.
When Tony is being chased by Rhody and the drones, drone 303 is shot down by the ground artillery/flak drones. Later, when Tony is under the bridge, another drone goes down after hitting a pillar. This drone is shown as 303 also, and 305 is already down.
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.
At the 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 Ivan's father, Anton, is watching the news when Tony reveals, he doesn't have the cards in his hand like in the first movie.
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.
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.
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.
On the first half of the movie, 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.
In several scenes you can clearly see the "Hall Of Armor" in the back ground. Each of the Ironman Mark Suits have arch reactors in the chest so it is possible Rhodey could have piloted the Mark II suit.
Mirrored Shot: When Whiplash (Mickey Rourke) attacks Tony Stark at the racetrack, after Tony puts the portable Iron Man suit on Whiplash gets hold around Iron Man's throat using his right-hand whip and starts electrocuting him. Then it changes to a close-up of Whiplash enjoying his work, however, he is clearly holding his left arm forward and when it goes back to Whiplash moments later he's using his right-hand whip again, revealing a flipped shot.
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.
The goof items below may give away important plot points.
At the end when Senator Stern presents the medals to Tony Stark and Rhodey, Tony Stark puts his arm behind the Senators 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.
During the action scene at the end, 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.