Continuity mistake: When Eddie Murphy's assistant makes assumptions about why Jack isn't speaking, he throws his notepad down and has empty hands as Jack pushes him out of the office. When the angle changes, he has a notepad in his right hand.
Continuity mistake: In the scene near the end of the movie where Ellen Miller asks Robert Miller to lift up his shirt, and then slaps him in the stomach with a newspaper, we see that his right shoulder suspender is properly positioned, however in the next shot from behind him his suspender over his right shoulder appears to be twisted 180 degrees. As he turns to walk into the inner bedroom the suspender is once again back to a proper fit.
Continuity mistake: When the mean Santa puts the little girl in his lap and asks her what she wants, she's wearing gloves. When it cuts to a different angle, suddenly her gloves are gone.
Factual error: When Dave shoots Justin 8 times, he empties the magazine of his semi-auto handgun, but he continues pulling the trigger, and the gun clicks several times. Semi-auto handguns do not "click" when they are empty, because it's impossible to pull the trigger. Also, the slide of Dave's handgun does not lock in the open position when the magazine is empty, as it should.
Continuity mistake: Alexandre Lagarde puts his fork into the plate of the attractive client, much to the scorn of her husband. The morsel in close-up and the one she actually puts in her mouth are different. (00:06:10)
Other mistake: During the end credits, there's a misspelling. An 's' is missing from 'First Assitant Camera'. (01:33:05)