Other mistake: When Rick and Ardeth Bay save Evie from the warehouse after Imhotep is resurrected, there are four mummies chasing them when they get on the double-decker bus. Rick shoots one of the mummies and "kills" it. He shoots another one in half and goes to the top of the bus to fight another one. The top portion of the mummy that got shot in half then fights Ardeth Bay. Evie kills the mummy that got shot in half and the top part of the bus gets torn off by the bridge and kills the mummy Rick is fighting. John stops the bus and they all sign with relief. Whatever happened to the fourth mummy chasing them? (00:43:20 - 00:46:40)
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.
Other mistake: When they are flying the dirigible through the night you can cleary see that there is a repeated pattern in the stars.