Character mistake: When Billy comes back from high school to visit his 3rd grade class, Ms. Vaughn is teaching prime numbers. The board reads "1, 3, 5, 7, 11" with the words "prime numbers" below it. "1" is not a prime number and it is written on the board, and "2" is a prime number and it is not written on the board.
Billy Madison (1995)
1 character mistake - chronological order
Directed by: Tamra Davis
Starring: Adam Sandler, Bradley Whitford, Darren McGavin, Bridgette Wilson-Sampras
Continuity mistake: When Billy is in first grade, Miss Lippy sits all the kids down in a circle for story time. One little girl goes up to Billy and says, "You have a mis-shaped head.", while she stands in front of Billy. In the very next shot, you see her stepping over Billy's leg to sit in front of him. (00:18:50)
High School Principal: Mr. Madison, what you've just said, is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response, were you even close to anything that could be considered a rational thought. Everyone in this room is now dumber for having listened to it. I award you no points, and may God have mercy on your soul.
Billy Madison: OK, a simple "wrong" would have done just fine.
Trivia: The pool that Billy appears in is of the exact same set of pools Navin R. Johnson [Steve Martin] used in The Jerk.