Deliberate mistake: When Janine smashes the mirror she takes it directly off the wall and raises it above her head, and the reflective side would be facing behind her. The camera immediately cuts to a front view as she's throwing it down and the reflective side is in front. This was probably done for dramatic effect so that the reflective side would hit the ground first.
He's Just Not That Into You (2009)
1 deliberate mistake - chronological order
Character mistake: About 3/4 of the way through the movie, when Jennifer Aniston is talking to Ben Affleck, she calls him Ben instead of his character's name Neil.