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.
Stupidity: When Evie's ladder moves away from the bookcases, she can easily put her hands on the top of the bookcase and ease back against it just like she was before. It wouldn't cause the domino effect because it wouldn't have enough force if she was stabilized by her hands.
Suggested correction: She was pretty terrified, trying not to lose her balance, and calling for help. Placing her hands on the bookcase would have required her to take at least one of her hands off the ladder, and she was probably scared that she might have fallen if she did that. It's not really a stupidity when a character does or doesn't do something in a moment of fear.