Crew or equipment visible: Earpiece visible in Dane Cook's ear while singing the "Piggy-nose" song which then disappears.
Continuity: When Marie is making pancakes, she picks up the syrup to pour on Dan's pancakes with her left hand and starts to pour, then in the next shot she is pouring with her right hand.
Errors made by characters (possibly deliberate errors by the filmmakers): The cop takes Dan's driver's license after his accident and then later Dan says he can no longer drive because he doesn't have a license. Although the police can take your license in lieu of a cash bond, they can not take away your driving privileges. You can still drive while waiting for your court date by using the ticket as your driver's identification. Typically only your state's DMV or a judge can revoke your driving privileges.
Continuity: In the scene where Dan is talking to Cindy and Jim, the father and daughter that are going to syndicate his column, you can see Mitch's chair next to Dan move close so that Mitch's leg is touching Dan's and further away, then close, then far again to Dan's chair.
Audio/visual unsynchronized: When Dan drives his car, you can hear a diesel engine and when he starts it back up you hear a gas engine crank.
Factual errors: Dan's car, a Mercedes 300 turbo diesel, is shown filling up at an unleaded gas pump.
Continuity: During the end credits when everyone is dancing in a circle, Marie's strap on her dress is falling down on her arm, then it cuts to a different angle and the strap is magically back up on her shoulder.
Revealing mistakes: In the second shot of Dan trying to get up after Mitch hits him at the bowling alley, a bald man in a sweater can be seen behind Dan scrambling to his right to get out of the shot.