Continuity mistake: In the scene were Hans tries to hang himself, you can see that the chandelier falls down but in the next scene when O.J the owl flies underneath it, it is still there.
Revealing mistake: When Ashton Kutcher drops all the mice, it is obvious that one of them is a toy mouse.
Continuity mistake: When Tom is on the bed with Tina and Audrey during the breast lump examination part, when the camera is positioned behind the trio they are shoulder to shoulder really close on the bed, when the camera is in front there are a couple inches in between them and they are sitting spaced further out.
Revealing mistake: In the scene where O.J. flies into Tom's car and the camera does a side shot, you'll notice that the background isn't moving.
Other mistake: In the scene where Tom goes to look for O.J. at the house with the girl who had the accident, he talks to the man in the wheelchair. When her father tells the man in the wheelchair to leave he bumps a table, the table falls and so does a red vase, the vase makes a crashing/breaking noise, but it is never shown as being broken.
Deliberate mistake: Whenever O.J. the owl is flying, there is the sound of wings flapping that sounds almost like a chicken flapping its wings. The flight of an owl is almost silent.
Audio problem: Tom is fighting TJ and we hear glass breaking as TJ falls backwards against a curtain, but then the curtain gets pulled down and the unbroken window is seen to the right of where the curtain was hanging.