Revealing mistake: After the Deathmobile ramming, when all the grandstand participants are in the heap of broken two by fours, you can see several chainsaw gashes in the structure made by the crew in order to pre-weaken the grandstand and facilitate its collapse.
Continuity mistake: When the Fraternity house is being taken down, the Greek letters switch places. (01:06:05 - 01:06:55)
Factual error: At Professor Jennings' place, the stoned Boon and Katy sing "Hey Paula." The song was only pressed in November 1962 and didn't break into the charts nationally until late December of that year, whereas the scene depicted takes place sometime in the autumn of the same year, before the song would've even been recorded.
Factual error: The car Flounder drives is a 1964 model, built beginning late in 1963, but the events of the movie take place in 1962. (00:45:40 - 01:08:25)
Factual error: In the scene where Pinto buys/shoplifts food from the grocery store and meets the Mayor's daughter, the cash register has an LCD display. A little too futuristic for a flick set in '62. (00:47:30)
Continuity mistake: In the scene where Otter and Boon are hitting golf balls near the ROTC drills, Otter puts down the golf bag he is carrying and draws a club. The camera moves to the ROTC trainees, and when it comes back to the golfers, the bag is back on Otter's shoulder and there is no club out of the bag. (00:20:10)
Revealing mistake: In the scene where the Mayor is giving his speech just before the parade begins, there is a man sitting in the bleachers behind him making bizarre faces and hilarious facial ticks in plain view of the camera. (01:34:05)
Continuity mistake: When Otter is making out with Shelly from Dickinson college, in the back of the car she is shown with her bra off, and it is hanging on her right arm by one strap. When the guys come running out of the club seconds later to make their escape, Shelly is shown jumping out of the car and diving through the window of the car parked next to it, but her bra is now on and hooked as if it hadn't been removed yet. (01:16:30 - 01:17:15)
Continuity mistake: During the toga party, the mustard stain on Bloto's toga, disappears and reappears. (00:55:45)
Continuity mistake: Before the hearing, Katy and Boone are talking at the bottom (half) of a stairwell when Otter comes down with a briefcase in his right hand and he puts his left hand on Boone's shoulder. In the next shot the briefcase is now in his left hand with his right hand on Boone. (01:00:55)
Factual error: When Larry and Kent first arrive at Delta house, and again after the new pledges are accepted, the Kingsmen version of "Louie Louie" is heard playing. This version was not recorded until April 1963, but the movie takes place in the autumn of 1962.