Continuity mistake: In the scene where The Thing and Human Torch are arguing in the lobby you can see in one scene the door leading to the outside with people around it Then, when Invisible Woman comes, Human Torch heads out through a different door with nobody around.
Continuity mistake: When Doom enters the elevator after arguing with Reed he is holding his gloves in his hands. In the next shot he pulls off a glove and punches the wall.
Continuity mistake: When Johnny is walking out of the dirt bike stadium, he has his arms around two women's shoulders. The shot changes, now the two women are holding on to his arms. The shot changes again, and now his arms are free. It happens too fast for him to just let go of the women.
Continuity mistake: After Johnny Storm jumps from the Baxter Building, a close up of him coming from the left is inverted, as seen from the inverted "4" on his chest.
Continuity mistake: Vic offers to take Sue's things to one of his condos. While he says "You'll have 'round the clock care'" he is holding dark-colored pants. The camera cuts to Susan while she says "Thank you, thats very generous." When the camera cuts back to Vic, he is now holding blue pants with a light-colored shirt wrapped around it.
Continuity mistake: When Mr. Fantastic is writing a problem on his chalkboard, right before the camera switches to Von Doom picking at his scar, you can see that Mr. Fantastic already wrote 4= Sxlo -4 and underlined it. When the camera goes back to Mr. Fantastic after the picking of the scar, he is now writing 4= Sxlo -4 and underlining it.
Continuity mistake: In the scene where Mr Fantastic walks in on Invisible Girl as she steps out of the shower, we see her covering up with a red towel, but in the next shot, it's a brown towel.
Other mistake: Julian McMahon's real Australian accent slips through when his assistant asks him if he should rest and McMahon says, "Later. First I have some unfinished business to attend to."
Factual error: When Reed and Sue are testing the Human Torch's powers, they claim that a temperature as high as the Human Torch's (5000 K to 6000 K) will "ignite the atmosphere and destroy all life". This is incorrect. Many experiments in the lab and on the field have produced temperatures several orders of magnitude larger than the temperature of the Human Torch on a similar scale. Nuclear explosions can generate temperatures in excess of 8000000 K, and temperatures produced by the largest X-ray generator (the Z machine) have been as high as 3700000000 K. Such tests have not ignited the atmosphere.
Continuity mistake: When Sue strips down on the bridge, Reed takes off just before Johnny bends down to pick up her clothes. He only grabs her shirt, jacket and pants. When we see Sue climb on the cab, she also has her shoes back.
Continuity mistake: During the rescue scene on the bridge, just before Reed rescues the falling fireman, it shows a shot of two other firemen. one is on top of the truck while the other is hanging from the end of the ladder. as Ben is pulling the truck back on to the bridge, there are now three firemen on the ladder near the back of the truck. but as the Ben pulls the truck back on to the bridge, you can see that there are only two firemen, one still hanging from the end of the ladder and the other half way along the ladder.
Continuity mistake: Just before Victor Von Doom proposes to Sue Storm, he kisses her on the hand. He holds her hand near his face, but in the next shot, it is down near his waist.
Continuity mistake: In the scene where Vic shows Sue the world from the ship, it goes to a shot where Reed finds a problem, when he says "thats impossible it should be 7 hours", The screen show H2 9.44, the next shot it changes to 9.44, the H2 is gone.
Continuity mistake: There is a boat coming into shot just as the ladder on the fire truck stops extending over the river. The boat is not seen in any other shots.