Continuity mistake: During the detention scene, the teacher comes in and you can see there isn't anything on his rear end. As he leaves, you can see toilet paper hanging from his rear. This was because a scene never made it into the movie where the teacher's office is in the mens restroom. Also confirmed on cast commentary.
Continuity mistake: In the beginning scene where Janey pulls out her vibrator, the red slider button is all the way to the top. Then seconds later she is seen turning the vibrator on by sliding the switch upwards, where it already was.
Visible crew/equipment: In the scene where the three boys are watching the girl go to the bathroom, the roof collapses and the girl, the boys, and a teacher are sprayed from the toilet. You can see the outline of goggles, especially on the girl's face.
Continuity mistake: When Janey is laying on the couch talking to her dad, in the closeup shots her hair is perfectly neat in the ponytail. From distance shots, some of the hair on top of her head is out of place. Then at the end, the father ruffles her hair and it matches the misplaced hair seen earlier in the scene.
Factual error: Jake hangs a Princeton banner in his home. The colors of the banner are brown and yellow. But the colors of Princeton are orange (primarily) and blue.
Revealing mistake: In the end at the airport, when Ricky walks up to the line to give his part of the story, you can clearly see a light reflecting off the black cap on Ricky's tooth, to make it look like he has lost one.
Continuity mistake: Just prior to Janey and her dad having their Father-Daughter talk on the couch, we see from over her shoulder that her robe is closed. The next shot of her though (looking down) her robe above the waist is open. In both shots she is either sleeping or dozing so would not have opened it herself.
Continuity mistake: As Jake attempts to convince Janie not to board the flight to Paris, the top button hole on his shirt alternates from being empty to having a stud.
Continuity mistake: At the beginning of the football game against the North Compton Wildcats, the team runs out on the field. It cuts to a scene of Jake waving at Janey and in the background the team is going through some drills. It then cuts to another shot of the team running onto the field.
Continuity mistake: Towards the end of the football game when Jake throws the ball on the scoreboard there are 32 seconds left and where it says "Reggie Ray's Concussions TO GO" it says either 10 or 0 where as before it said 1. But when Reggie gets hit with the football the scoreboard goes from 1 to 0 and the timer as at 0:00. It is unlikely that that whole play took a full 32 seconds.
Continuity mistake: In the scene where Jake sings "Janey's got a gun," the people in the crowd behind her scatter. One girl (in a tan coat) is carrying her painting. In the close-up shot the painting has fallen from one of the clips holding it, but in the wide-angle shot the painting is on securely. There is also a girl in blue jeans and a blue sweater and purple shirt sitting to Janey's right. She runs past Janey off the screen. In the next shot (a wide angle) the girl is seen again running behind Janey. Just watching it I think the same could be said about the other people in the class as well.
Continuity mistake: When the boys are watching the girl use the loo, it shows a shot of the ceiling in Janey's classroom (just before the vent falls) and the ceiling is smooth, but when they fall you can see a part of the ceiling has been replaced by some loosely placed white bricks, which would fall easily. When they're on the floor with the turd all over them there are no bricks in sight.
Continuity mistake: In the scene where Jake enters Janie's basement where she is painting, (after he says there was a hole in her house) the paint on the brush is red, in the next shot it is greeny-blue. She would not have had time to clean the brush as the different shot lasts for about 3 seconds.
Continuity mistake: The stupid fat guy's supposed to die because he had so many concussions, but in the scene after the football game when he's on a stretcher and it collapses in the background you see him putting his hands out to make sure he doesn't get hurt during the fall.
Continuity mistake: When Catherine is taking off Janie's glasses she leans right in, but when the camera angle changes it shows this to be a larger gap. when the camera flicks around again she appears to be leaning in again.