Revealing mistake: After the power goes out at Sarah's hospital, she lights a candle. While she's walking along with it, it's obvious it's not made of wax. It looks like it's made out of plaster.
Revealing mistake: When entering the tomb there are quite a lot of shadows on the walls and statues. We are supposed to be in a sealed tomb. Where is all the light coming from? You can tell by the shadows that light is coming from multiple locations, not just the priest's lamp.
Revealing mistake: The two workers to the right of the entrance are fake digging. Their picks never touch the ground. (00:27:20)
Chosen answer: Yes. It may have taken so long because the blood was probably pooling at the back of her head, which caused her to pass out, then finally built up enough pressure to gush out of the cut or fracture at the back of her head.
Macalou