A box of detergent appears and disappears from a washing machine between shots.
When Ned is in front of the elevator it opens and Julia comes out. A front shot of Ned shows him with his hair all over his face. Then another shot shows his hair to the sides and then it changes back to cover his face.
At the very beginning of the movie, a minor character buys two packs of smokes and the register says $3.50. In 2004, they would have been much more expensive.
When the killer reappears through the window he enters making a spectacular jump, even there is not enough space behind the window to execute it, as it is shown after he falls down.
When Nell is writing the note to Julia the sound of the pencil on the paper mismatches the action.