Continuity mistake: When Peter first leaves his house near the beginning of the movie, he throws his empty bottle at a lawn chair, and it bounces off onto the ground. In the next shot, when he drives away, you can see nothing on the ground and what looks like the bottle now lying on the chair. (00:03:20)
Continuity mistake: When Peter walks into Average Joe's in the beginning you see Owen leaning over the counter reading. His hair is parted to the right and has spots where you can see his forehead (it's grouped). But in each shot where it focuses back to Owen his hair is different each time, sometimes combed nicely with no empty spots. (00:04:00)
Continuity mistake: When Gordon is talking to Peter about the OSQ magazine about midget tossing, right before Gordon hands him the magazine, Peter has an orange juice carton in his hand. In the next shot you see him holding the magazine with both hands empty, with not enough time to get rid of the orange juice. (00:04:40)
Continuity mistake: When Martha Johnstone falls on Justin during the cheerleading tryouts, her skirt falls up and is laying on her back; they show this in a front view; but when they switch to a side view, her skirt is back down covering her bottom. (00:06:35)
Continuity mistake: When Peter opens the door to his file closet to show Kate his paper work, the door on the left changes from being open wide to just slightly open throughout the scene. (00:09:40 - 00:09:43)
Continuity mistake: In the first scene that Vince Vaughn goes to global gym to confront Goodman, Vince and Ben are talking to each other. During the conversation, you can see a woman working out on a fitness machine behind Vince. When the shot widens as they are leaving, neither the machine nor the woman is there. (00:10:50)
Continuity mistake: When Justin is trying to rally all the boys behind saving Average Joe's, he throws a blue icepack on the couch when he stands up. When it focuses back on Gordon, the icepack is gone. When they show Gordon again, the icepack is back. (00:13:15 - 00:13:50)
Continuity mistake: In the first shot at the car wash, there is a white car parked beyond the lifted truck, in the background. In the very next shot that car is gone. The dog also goes from lying down to instantly sitting up, between the two shots. (00:14:30)
Continuity mistake: When the guys are all sitting around (after the car wash) they are throwing ideas to save the gym. In one shot Gordon pulls his magazine out of his bag, but a split second later in a closer shot he pulls the magazine out again. (00:15:15)
Continuity mistake: When the six main characters are watching the movie on how to play dodgeball, a young Patches messes the little boy's hair, leaving it sticking up in the back and mildly flat in the front. In the very next shot, the little boy's hair is neat and all flat. (00:23:50)
Continuity mistake: In the qualifier between Average Joe's and the Girl scouts, Peter starts talking to the girl he hit while another girl throws a ball at him. The girl who throws the ball is almost right in front of him but you can see the ball that hits Peter comes in from the right of screen and hits between the top of his left shoulder and the bottom of his neck. (00:27:30)
Continuity mistake: The hairy girl scout is disqualified at the end of the game but she wasn't one of the six players in the beginning of the game. (00:27:35 - 00:29:30)
Continuity mistake: When White and Peter are going back and forth at each other in the Dirty Sanchez, White's "G" charm around his neck keeps going from forwards to backwards from shot to shot. (00:30:40)
Continuity mistake: After White knocks the food onto the Average Joe's players in the bar, Owen is holding a martini glass in his left hand. The following shot, the martini glass has disappeared. (00:32:35)
Continuity mistake: When the waitress gets pushed into the table at the Dirty Sanchez, the food splatters everywhere, but none of it gets on Owen; he is completely clean. Then, they have a shot of him directly afterward, and he is completely covered in food. (00:32:35)
Continuity mistake: When White pushes the waitress into the table at the Dirty Sanchez, she takes the tray with her as she stands up and walks away. In the next shot, Gordon moves the tray off the table. (00:33:55)
Continuity mistake: At the bar when Goodman says "Best bring your bib" to Peter you see Goodman lift both his hands. When it cuts from behind Goodman you should at least see his left hand, but it isn't up. (00:34:00)
Continuity mistake: When a tray full of food falls on the Joe's Squad, Justin has some food on his right cheek. A few seconds later it's clean, and there's some gravy on his left cheek. (00:34:05)
Continuity mistake: When O'Houlihan throws the spanner at Owen, you can see it is a different spanner lying on the floor beside Owen two shots later. (00:36:15)
Continuity mistake: When Michelle takes the screen prints of Kate throwing the dodgeball at his cutout, the screen capture on the monitor differs from what he shows to Goodman at his office. The shot is flipped over and from a different angle. (00:40:05 - 00:41:20)
Answer: There were many celebrity cameos throughout the film. It's just kind of strange that Chuck Norris would do this.