Other mistake: When Buddy's brother is reading Santa's list he reads the newscaster's wish he looks and mutters something about letters meaning they were in alphabetical order. However when he is saying random names he does not turn the page and the names are NOT in alphabetical order.
Visible crew/equipment: In the scene where Buddy and Michael are leaving the school, a crew member is visible in the bottom left of the shot. At first, he is just standing there, but he then tries to hide inside a doorway.
Continuity mistake: In the very beginning, when the nun puts the baby in the crib, she puts a blanket on him he pushes it down to his feet, then the camera goes to the nun walking out of the room, and when we see the baby again the blanket is covering him again.
Revealing mistake: While we see Buddy drinking the entire bottle of Coke, it is quite obvious that he is not actually drinking it. Buddy has his lips firmly sealed around the end of the bottle and gulps down the entire lot. If he was drinking it, the bottle would have caved in as no air was getting inside. It was not even possible for him to blow air from his nose back into the bottle due to the fact that he is continuously gulping.
Continuity mistake: The scene in James Caan's publishing conference room when Buddy and Myles Finch are wrestling results in Buddy's foot hitting the far left picture of three pictures on the wall. The picture comes crashing down and you hear breaking glass. The next shot reveals the fallen picture back up on the wall unbroken. It is followed by the next shot showing the picture gone off the wall again.
Continuity mistake: During the scene where the stepmom is eating spaghetti, you can see she is only using a fork and there is a knife next to the plate. In the next shot the knife is now on the plate despite the fact she only uses the fork to eat throughout the scene (also there is no sauce on the knife so very doubtful she used it to help her eat the spaghetti). In the following shot of her the knife is back by the side of her plate again.
Continuity mistake: In the scene when Jovie is asking Buddy why he was in the girls locker room, the amount of people in the background changes each time it cuts back from Buddy to Jovie. It goes from originally five people to three, back to five and so on. This is obviously a mistake because the characters in the background are the same when it's five and the same when it's three.
Continuity mistake: When Buddy eats dinner with his dad and "family", there is a piece of bread in front of the dad that has a bite taken out of it. Throughout the scene the bread changes positions.
Continuity mistake: In the scene where Buddy is singing along with Jovie (who is in the shower), it shows Jovie singing and her hair is obviously wet. However, when she stops singing because she hears Buddy, the shot cuts to Buddy on the counter, then back to her. Her hair is dry and stringy on the bottom. It is more obvious when she sticks her head out of the shower.
Continuity mistake: When Buddy chugs the soda, the bottle rotates in his hand depending on the shot. In views from two different angles, the Coke logo is always visible.
Revealing mistake: In the beginning of the movie, there is a scene where Buddy hits his head on the roof of the house as he's running out. You can obviously see a machine pushed the snow forward to land on his head. [May be easier to see in fullscreen version].
Continuity mistake: In the scene where Buddy's Dad is talking to his manager about the missing pages in the book, and how the manager thinks that the company will post a minus eight for the quarter and storms out of the room, Buddy's Dad's arm is resting on a piece of paper that is almost directly in the center of the table, and after it cuts to the manager and back to Buddy's Dad, the piece of paper is close to falling off the table.
Continuity mistake: When Papa is showing Buddy the sled at the beginning of the film we see the Clausometer (the middle odometer)and the indicator is pointing to the left at around 15 (9pm position). As Papa gets in the indicator is now pointing at around 35-40 (10pm position). Later in the scene when it show a closeup of the meter it is back to 15 and then the last shot of it its 35-40 on the meter. The changes are instantaneous between shots and there is not enough time for them to move that much.
Audio problem: When Buddy asks Jovie out for food, as Buddy and Michael leave you can hear a male voice say "It's okay" but it there's no male close enough to whisper. (Nor a reason for anyone to).
Revealing mistake: When Buddy is chugging the bottle of Coke, there is a shot taken from behind Buddy. Look at his arm when this is happening. The dark line running down his arm is the tube used to carry some of the Coke away, so Will Ferrell didn't have to drink the entire 2 liters.
Visible crew/equipment: In the scene in Central Park when Santa's sleigh has crashed and Buddy is repairing the engine, the line that is holding the reindeer in place is visible on the lead reindeer. Not the harnesses that are around each reindeer but the line that is keeping the lead reindeer leashed to the ground is visible.