Revealing mistake: Towards the end when Harmony calls Perry's phone as she's lying on the ground, Harry grabs the phone and looks at the caller ID to see her name. Unfortunately that's not the display showing who's calling. Anyone who has a Nokia phone will recognise that that's showing the contact list with just two entries - Harmony and a random number. The fact that it says "contacts" at the top of the screen is a bit of a giveaway.
Revealing mistake: When Chris and Jamie are on their day date in the diner, Jamie has a grilled cheese sandwich with ranch on the side. However it is obvious that the bowl of ranch is empty. (00:33:10)