Continuity mistake: The invasion upon the city at the beginning showed the dog headed army pushing over an Obelisk (large granite pillar) which upon impact showed it separate into chunks similar to roman and Greek pillars, but these Obelisks were made of one single slab of granite so it should break and have slithers and chunks come off it. (00:04:10)
Factual error: When Rick uses dynamite to destroy the log bridge, the log snaps several seconds after the explosion has gone off. The force of the blast would snap it instantaneously.
Continuity mistake: When Alex moves the toilet on the train and looks down through the hole there is some water round the side. The camera then goes back behind Alex and you can see the pipe that was conected to the back of the toilet with a steady flow of water leaking out above the hole. The shot then goes back to above the hole and there is no water falling down. (01:04:35)
Continuity mistake: Right after the sun rises on the Scorpion King's pyramid, the following scene, which is approx. ten seconds later, the sun is directly overhead, then the shadows change lengths. (01:34:50)
Continuity mistake: When Evie is unconscious and being carried on the stretcher, you clearly see her head facing to her left in the close up, when the camera pulls away for a long shot you see her head facing to her right only to be quickly returned to the left for the next close up. (00:34:13)
Continuity mistake: After they've kidnapped Alex on Tower bridge, they raise it to aid their getaway. The next shot is of Imhotep and Anck-Su-Namun standing looking over the city from a balcony - you can see the bridge, and it's lowered. You might think that that shot takes place a while afterwards, and the bridge has since been lowered, but then it goes back to Rick and Evie, and you can both see and hear the bridge lowering back into place.
Continuity mistake: After the cast makes a getaway on the double decker bus, the little kid jumps on John's back and says, "Nice job." When the shot cuts, he is still there. In the next shot, the bus is pulling over to the side of the road and the boy is not on John's back anymore.
Revealing mistake: After Anck-su-Namun meets with Imhotep in the museum, he waves his hand over her face and there is a brief flashback of the two of them in ancient times. They kiss, and it reverts to the present, where Imhotep is still not completely regenerated. You can tell it's CGI because of how the tip of her nose disappears into his skin as they kiss.
Continuity mistake: When one of the men in red is looking at the pygmy in the tree, the pygmy's face is looking up slightly (right before the first man is attacked) and has his mouth relatively open. But, right before it wakes up, its head is slightly down, and the mouth is less open than it was before.
Other mistake: How would Alex know that Imhotep's water wall took out his parents? The matter of distance is debatable. But, the winding path that the dirigible took though the canyon, as well last the water wall, would block his vision.
Continuity mistake: When Rick turns around finds Alex, Alex falls back and his hat falls off and rolls back a few inches, resting a few inches from the top of his head. However, after Rick says his name, it cuts back to Alex and the hat is practically under his head, almost behind his back.
Continuity mistake: During the scene when Imhotep controls the water and raises it up he starts with straight arms, as shown in the shot with his back facing the camera. However in the next several shots showing him from the front he has bent arms, then straight arms from the back again.
Other mistake: Rick's son screams for him during the rescue from the pygmies and Imhotep, but how did Alex know his dad was running in to save him, if he thought they were killed by Imhotep during the river consuming the ship in midair?
Other mistake: When they are flying the dirigible through the night you can cleary see that there is a repeated pattern in the stars.