This slip-up comes, when Nicholas Cage's character is moving to Sarah, and he's packing his bags.

The Slip-up:

At first there's a glass on the right side, which is half full of something brownish (maybe whiskey)

Then he takes a bottle of transparent colorless vodka and fills the glass, to the half. After that they zoom out again, and then the glas is half full of that brownish liquor. After a couple of seconds of packing the glass is full again, of that brownish liquor.