Continuity mistake: During the scene when Van and his friends are riding in Van's golf cart, just after Van has sex with the secretary, the guy in the back is seen being licked on the face by the bulldog. When the camera cuts to Van he's not being licked. When the camera cuts to Van's assistant he's being licked again. This happens over and over.
Continuity mistake: In the last scene, at Van Wilder's party, Gwen is talking to Van Wilder and her bathing suit strap is on her left shoulder. When the shot changes, it has disappeared from her shoulder and is on her back. She wouldn't have moved it as her hands don't move in the scene.
Factual error: At the beginning of the movie Van tells the viewers that it is the beginning of spring semester at Coolidge College and it is obvious that the college is somewhere up north near Massachusetts because in the scene where Van is giving the basketball team a pep talk one of the players asks Van if he invited the girls from Mount Holyoke (which is in Massachusetts)to their party. Yet throughout the entire movie everyone is dressed in shorts and tank tops like its summertime outside when in reality January up north near Massachusetts is FREEZING...
Deliberate mistake: During the scene where Richard is playing croquet on the lawn in front of the Delta Iota Kappa house, the letters of the fraternity are visible on the front of the house. The Greek letter for "Delta" should be a triangle yet it is the letter "D" in the shot. This is presumably to follow the "DIK" joke that would not be as obvious if written in correct Greek letters.