Factual error: I counted five canopic jars, one of which has the head of a lion. In ancient Egypt there were only four canopic jars - Hapi, the baboon-headed god representing north, Imseti, the human-headed god representing south, Duamutef, the jackal-headed god representing east and Qebehsenuef, the falcon-headed god representing west. None have lion heads.
Factual error: Due to the Earth's rotation, the mirror system used to light the tombs would only provide light for about 4 minutes before needing readjustment (tested by the Mythbusters). This would be fine when there were plenty of priests around to adjust them constantly but the light level never changes even though we see Rick and Evie for several minutes at a time.
Add timeGrumpy Scot
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.
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.
Factual error: In the scene where the Americans find the chest containing the canopic jars, the egyptologist reads the text from left to right. However, the text actually begins from the middle and goes to both directions: one sentence goes from right to left and the other from left to right (this was very common in Ancient Egypt as hieroglyphs could be written in both directions) So, as he started from the left, the highly trained egyptologist was actually reading the inscription backwards.
Factual error: After the American who wears glasses has had his eyes and tongue taken by Imhotep, he still is able to articulate words pretty well, which, if his tongue was really gone, would be impossible-try talking without moving your tongue sometime, and see how unintelligible you are.