Character mistake: Dwanye Johnson is called onto the ice, the first thing he does is throws a player through a glass pane. The player looses a tooth. The close up shows that the tooth is a molar, but the commentators say, seconds later, "Ohhh that's an incisor!" (00:01:00 - 00:02:35)
Continuity mistake: When the "Toothfairy" met the cat for the first time after they fall out of the bed, you see only a piece of block, and 2 shots later there is a skateboard next to it . (00:35:45)
Visible crew/equipment: When Rock is learning to fly, the top of the cyclorama wall is visible and the top of his flying rig harness is very visible with attempts to blur by post production on only some parts.
Plot hole: Obviously, tooth fairies are real, in this movie at least. During the movie, Derek has to retrieve each child's tooth and put money under the pillow. He's paged as soon as the kid loses the tooth, since he often has to wait till the kid goes to bed before intervening, and he is required to do it as soon as possible. But parents are doing the same, and at one point in the movie Derek actually stops a dad that just did the swap and extorts the tooth from him. That of course creates a parodox: the majority of parents in the world apparently have been subjected for centuries to the freak occurrence of finding already under their pillows mysterious money and their children's baby teeth missing as they go do the deed themselves. You can't have both the fairy and the parent do the same task.
Continuity mistake: When the Rock enters the first kid's room, pay attention to the blue building block on the floor and how it is turned. Just for the shots where the cat arrives and The Rock has to hide behind it, the block rotated 90°. It goes back to how it was a moment later, otherwise the curved path would not face the door and the Rock couldn't fly towards the door. (00:33:30 - 00:36:15)
Continuity mistake: Right as The Rock lands in the Tooth Fairy world for the first time in his dazzling tutu, one of the first fairies that cross his path is a black fairy, moving from what would be The Rock's right to his left. In the next shot he's all the way to the Rock's right. In general in the scene there's a lot of extra recycling, a Hispanic fairy with heavy makeup and big cheekbones, quite recognizable, that keeps advancing behind The Rock without ever really moving. (00:11:55)
Continuity mistake: The Rock is goofing around with his fiancee's little girl playing a vampire. Randy scoffs and goes to open the fridge. In the first shot he's reaching for both doors, in the closer shot he is opening just one, brief cutaway shot and then he's re-opening the same door. (00:05:35)
Other mistake: At the last game when Derek flies out of the rink, the crowd is standing quiet and still from shock at what they've seen. When the camera is panning across the crowd, if you look in the right hand side, towards the top, there is a lady with black hair and a red coat waving her arms and looking straight at the camera (like the extra is trying to be seen by family and friends). (01:20:55)
Deliberate mistake: All Minor Hockey Leagues in North America require players to wear visors with their helmets.