Revealing mistake: When Rolfe is walking down the hallway to Sally's apartment, there is an orb where the hallway is lighter colored and his legs seem to jump and undulate due to the special effect used to hide the fact that the actor is actually full-sized, walking on his knees.
Revealing mistake: The first night Ben brings Andie home, he starts the music on the CD player, but no CDs are spinning at all. Yet, the music still plays. He also changes the track mid-scene, and still no CD is spinning.
Revealing mistake: One of the accountants' computers has no power cord attached to it.