Continuity mistake: When Vernon walks over to place a pencil and paper on Allison's desk, the number of pencils in his hand switches from several to just one in between shots. (00:06:50)
Continuity mistake: When Bender tosses the crumpled sheet of paper between Claire and Andrew, his right arm is fully extended into the air at first. But by the next shot he's seen tossing it with his elbow resting on the desk instead. (00:09:45)
Continuity mistake: After Molly Ringwald does her trick, she puts the lipstick away twice. It has a shot of her putting it away from the front and then another one from the back.
Continuity mistake: Claire's hair changes in the library scene. First, it's flat, then she's got it poofed up with a flip on the ends.
Continuity mistake: When Vernon is looking in the basement files and Carl walks in, the card in the drawer label holder is tilted and it stays this way for a few shots. When Vernon claims it's a highly sensitive area, the card is now straight, but in the shot after that it is tilted again.
Continuity mistake: When Bender takes the screw out of the door, the chair that Vernon tries to use to keep the door open is not there when he walks in. When he goes to use it, however, it is right next to him.
Continuity mistake: The scene where Bender and Vernon are in the closet, Vernon tells John to take a swing at him and points to his chin. Now in the frontal view he is pointing to his chin with his right hand, but from the back view it shows him pointing with his left hand, then it goes back to the front with him pointing with his right.
Continuity mistake: When Judd Nelson enters the library, he walks up to Brian's table and motions to him with his hand to move to another table. He uses his left hand, but when the camera-angle changes and shoots Judd Nelson from behind, he is suddenly pointing with his right hand.
Continuity mistake: When Bender is escaping through the ceiling, his wallet chain is seen on his left side. That is where it is throughout the whole movie. Except when he's crawling back to the little room through the ceiling, it is seen on his right side.
Continuity mistake: When Claire is dancing on the staircase, the giant wall clock behind her shows a little past 3:30. However, in the next shot when Bender is riding the sculpture the clock now reads before 2:30.
Continuity mistake: As Bender and Vernon go back and forth about Saturdays, Bender's hair goes from down and slightly in front of his right eye to back and exposing his face.
Continuity mistake: After the whistling scene, Bender is holding a pencil. When Andrew is talking you can see Bender in the background playing with the pencil. The camera cuts back and forth between him and Bender throughout the scene. But when the camera zooms in on Bender when he's talking, he has nothing in his hands.
Answer: Bender found the shoe in the gym, and decided to wear it. When the principal kicked the basketball, Bender jumped out of the shoe. He left with his boot, and was wearing it when he arrived at the library.