Continuity mistake: When Spivey is "sucked dry" by Imhotep, you can see his face is totally decimated. Yet, when Anck comes in later, his face is totally intact, with only a gray discoloration. An easy way to see this is to look at his lips: as he gets killed, they curl and rot completely off, but they are perfectly present on his corpse.
Continuity mistake: In the scene where Rick and Eve are hanging from the bars in the flooding tunnel she has her green top on. The water hits them and then they are haning from the bars, but the green top is gone. Then, when the wall breaks and the two of them spill out, she has her green shirt again. (00:16:15)
Continuity mistake: When Patricia Velasquez has her first flashback to her past life, she is in a room with Imhotep. If you look closely at her shoulders in an up close shot, her hair is in front of both of them. Then we cut to a shot of the room from outside (we can see the room through the balcony) and the hair is still over both shoulders. Then we cut to another up close shot of Patricia, and we see that her hair is over her left shoulder, but behind her right one. (00:49:15)
Continuity mistake: When Evie gets stabbed by Anck-su-Namun, she falls to the ground with her hands clutching the wound on her stomach. Her hands do not leave her stomach (even though her arms are out of the shot, her shoulders stay still) but in later shots her arms are spread out, away from her body.
Continuity mistake: Right after Alex scares Rick, we see him holding a stick with fire on top. Every time they change camera angles the amount of stick between his hand and the fire changes dramatically. Its not possible to make the stick move up and down that fast with one hand without hurting himself. (00:06:15)
Continuity mistake: When Alex is taken on the train, Anuk-su-Namun puts her hand under his chin and kisses him, but when the camera angle changes, her hand isn't under his chin. (00:49:00)
Continuity mistake: In the first movie Ardeth Bay has tattooed on his forehead a bunch of hyroglyphs, one of which is a half moon shaped heiroglyph, but in this movie he is missing the half moon shaped tattoo. (00:29:10)
Continuity mistake: In the first movie, one of the canopic jars is broken. In this movie, they are all perfect.
Continuity mistake: In the scene where Rick and Ardeth are driving up to the museum to rescue Evy it is raining hard, very hard, yet when they get out of the car to strap on their weapons of choice, there is no rain to be found. Not even dripping off the tree limbs. (00:34:40)
Continuity mistake: When Alex is on the scaffolding in the temple, there are the three bandits looking through some old pots and other bits. You see one of the bandits pick up a pot and lean a boat over to the side. When you cut to the scaffolding where Alex is, he does the exact same thing again, he lifts the pot and tilts the boat.
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)
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: 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: When Imhotep is hanging off the ledge at the end, he yells to his woman to help him. After she leaves, he starts to cry. They show him crying and hanging on with his right forearm on the ledge, then it cuts to a shot of Rick and Evie, then back to Imhotep, but now he is using his left forearm to support himself. Potentially he could have swapped arms, but he doesn't show any sign of having shifted his weight, and it happens really quickly. (01:57:15)
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.