57 minutes into the movie, The Riddler and Two Face go on a diamond raid right after they meet. The Riddler smashes a case, pulls out a diamond and says, "Here's a good one!" while looking at the diamond through a collapsible magnifier.

Go back and you will see the one he is taking from the case is very large, but when the shot changes and he is looking at it through the magnifier, it is a much smaller diamond after which Two Face presents the large diamond.

This slipup is visible for about 30 frames.