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. (00:04:20)
Other mistake: Evie explains that if Imotep was resurrected he'd bring with him the ten plagues of Egypt. This is followed by (in no particular order) a plague of Locusts, Flies, Water running to blood, the sun being eclipsed and a plague of boils. At the plague of boils Jonathan says 'last but not least, my favourite plague - boils and sores'. How does he know this is the last plague? Aren't there supposed to be 5 more? (01:23:10)
Trivia: The 1999 film was not a remake of the Boris Karloff classic, but a remake of the 1968 film McKenna's Gold which starred Gregory Peck and Omar Sharif, thinly disguised and transferred from the American southwest to the valley of the Nile.
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.