Stupidity: It's stated that Imhotep will fear cats until he has fully regenerated and two different scenes show him fleeing in terror at the sight of a cat. Despite this, none of the characters that Imhotep is trying to kill that are fully aware of his weakness even think to have a cat with them at all times.
Phaneron
8th Feb 2016
The Mummy (1999)
4th Apr 2015
The Mummy (1999)
Other mistake: Despite nearly being hanged to death, Rick shows no sign of rope burns or bruising on his neck afterwards.