Continuity mistake: In the scene where Eddie Murphy is going into the crypt, he takes one of the lit torches. While they are trying to escape the skeletons, the door to the crypt closes and locks. When they show the shot of his son outside, you see two torches again. When he gets the doors open and they leave, you see one.
Continuity mistake: When Sara meets Master Gracey in the library after dinner, he startles her and she trips over some book. She picks two or three books up and has the book bindings in her right hand. The shot changes and instantly, the books have turned 180 degrees so that the bindings are in her left hand as she hands them off to Gracey.
Continuity mistake: In the scene where Michael sees the ghost ball for the first time, he screams and Megan comes in. Because of the shock, she drops her cellphone on the floor and we can see where it fell. In the next shot you see the cellphone, not on the same place Megan dropped it. Megan or Michael couldn't have touched it because they where shocked by the ghost ball and were looking at it all the time.
Other mistake: This mistake happens in the scene introducing the four singing heads on the Australian release DVD. They start singing when Jim and the kids turn the corner. According to the subtitles, they sing "When the cryptos creak and the tombstones quake, spooks come out for a swinging wake..." The subtitles are supposed to read 'crypt doors', not the incomprehensible 'cryptos'.