Continuity mistake: When Rick is fighting Benny on the camel when they are riding towards the temple Rick and everything else is in shadow in some shots even though the sun is high up and there are no clouds. (00:38:30)
Audio problem: When Jonathan and Evelin are about to board the boat after Rick gets on, Jonathan says "Yes, yes, you're right. Filthy, rude and a complete scoundrel, there's nothing to like there at all." Before he finishes his sentence it cuts back to Evelin, and his lips don't move. (00:23:30)
Continuity mistake: When Henderson gets killed by Imhotep in his hotel room, the shadow of his corpse being thrown shows it to be thrown quite a distance across the room, yet when Imhotep appears, and then walks off, Henderson's corpse is right by his feet. It was thrown much further than that.
Factual error: What is the 'Royal Air Corps'? It was the Royal Flying Corps until 1918, and has been the Royal Air Force ever since. (01:09:55)
Continuity mistake: Following the attack of the Magi on the adventurer's camp, the short sighted American's shaving foam changes from shot to shot.
Continuity mistake: In the scene where Evie, Jonathan, Rick and the fat guy drop down into the mummy preparation room, you see the fat guy pick up his tools and start walking forward, then in the next scene, you see the exact same thing. (00:41:15)
Continuity mistake: When they show Anck Su Namun committing suicide at the beginning, when the Pharaoh's guards show up she whips around to face them and all of her hair goes over her left shoulder. None is left on her right shoulder. However, in the shot from the front, she has half of her hair over each shoulder. (00:03:20)
Factual error: The sacred jars containing Anck-su-namun's organs are protected by a pressurized salt acid booby trap. The beginning of the film depicting Anck-su-namun's death is set in 1290 BC, meaning the trap must've been installed at this time, but salt acid wasn't discovered until 800 AD. (01:08:34)
Factual error: When Evelyn fights Anck-su-namun, Jonathan is struggling to read some hieroglyphics from the Book of Amun-Ra. Evelyn tells him that the word he can't remember is "Amenophis." However, "Amenophis" is not Egyptian: it is the Greek equivalent of the Egyptian name "Amenhotep" - "Amun is satisfied." In short, the name "Amenophis" could not have been written in the Book of Amun-Ra (let alone have any magical power over the undead priests) simply because it's not Egyptian.
Continuity mistake: You'll notice that they put a lot of emphasis on the sun rising and "showing the way." The sun then rises IN FRONT of them. When the camera gives us a view of the riders on the camels, the shadows from their hats fall directly on their faces, when instead there should be no shadows. When the camera moves to show them all riding towards Humanaptra, their shadows fall a little to the left and behind, like it's high noon or something. (01:37:45)
Continuity mistake: When Benny is looking for the black book in the office, he gets caught by O'Connell. When they are standing under the fan, you hear the scream of the Egyptologist. They all look towards the camera but when Benny runs out the window behind them, the Egyptologist is there. (01:18:40)
Continuity mistake: When Henderson shoots the burning guy to save Jonathan, I counted at least ten shots from his pistol. Also happens when Rick shoots, he seems to fire off more than the 12 shots you would think he'd be limited to.
Revealing mistake: When Evie is chained to the altar next to Anck-Su-Namun, the closeup of Anck-Su-Namun shows the bandages across her throat twitching slightly with the actress's pulse. The problem is, she hasn't been brought back to life yet.
Factual error: When Rick is running from the horsemen at the begining, he stops in front of a pillar and waits to be shot. We see the horses round the corner and rear back in fear and one falls over. We then see Rick again and then cut back to the horses, which have all disappeared. There's no way a horse could get up and run off that fast with a rider. (00:10:55)
Revealing mistake: When the boat with the Medjai is heading towards the ferry, you see the one attach the hook to his wrist. You can see the bulge of his fist at the end of his sleeve, where he attaches the hook. If he was really without a hand, it would only be as thick as his wrist.
Other mistake: When the locusts attack the camp, you see one of the workers get attacked and killed by them within seconds. Then, you see the Egyptologist covered in them. Why isn't he getting attacked and killed by them as well? You'd think that, just like the scarabs, they'd never stop eating.
Character mistake: Henderson asks the guy as he's leaving the room to get him some bourbon. They already drank in the bar and spat it out when they found out that everything had turned to blood, so it would still be blood.
Revealing mistake: When the scarab beetles surround Benni at the end of the film, watch closely... you can see many scarab beetles running directly "through" each other, revealing they are just a digital effect. (This is also visible in other scenes with the beetles, but it's most obvious in this scene, particularly in the first shot when the beetles begin to swarm towards Benni).