Revealing mistake: When Kate, Chris and Lord Arnaud are in the hidden monastery tunnel, there is an explosion that shows them the way out. One of them crawls forward a little and puts his weight down on a big chunk of stone, which flips about like it weighs nothing. It's very obvious that it's a piece of styrofoam rock. A piece of stone that size would not move as freely as this one did from just leaning on it.
Revealing mistake: When Chris brings the beers to Kate's excavation area and startles her, she then sits up and proceeds to turn down her iPod. However, she turns the wheel on the iPod clockwise, and for those of us who own iPods, we all know that either that scene was reversed, or she blew her eardrums out so she would not have to listen to Chris.