Continuity mistake: When Flounder and Larry arrive at the Omega house for the party, sunlight can be seen coming through the windows, although it was night when they arrive. (00:03:00)
Continuity mistake: When Pinto and Flounder visit the Omega house in the opening of the movie, notice the girls coming down the stairs. In the first shot they are there, the second shot they are not, then they are. (00:03:00)
Continuity mistake: When Pinto and Flounder attend the Omega rush party, a tasteful piano piece is playing. Niedermayer catches the eye of the brother at the piano, who smiles back over the keyboard. Soon thereafter, Niedermayer points out two important Omega brothers, who are standing in conversation across the room: Terry Auerbach, captain of the swim team, and Carl Phillips, editor of the Daily Faberian. The music has not stopped, but, when Carl turns to the camera, we see that he's the same guy who's supposed to be playing the piano. (00:03:15 - 00:04:55)
Continuity mistake: During the Delta Rush Party, Pinto (then just a pledge) got a beer. Notice that, as the scene changes camera angles, the heads on the beers go up, down, and up again. (00:07:30)
Continuity mistake: When one of the Delta Frat Guys is drinking beer in the frat, in his close up he is holding a mug by the handle, in the reverse shot he is not holding the handle. (00:07:30)
Continuity mistake: When Larry meets Karen Allen's character at the frat house, she offers him a beer. When you see the back shot of Larry, he is holding the beer glass in his right hand. When it switches to a frontal view of Larry, he is holding the glass in the left hand. (00:07:30)
Factual error: Bluto crushes a beer can against his forehead. Steel cans are too strong to crush like that. Aluminium cans weren't introduced until approximately 1965, although the movie was set in 1962. http://www.cancentral.com/brochure/historyTimeline_f.htm. (00:07:55 - 01:20:20)
Suggested correction: Maybe it's a joke about his thick skull/him being impervious to pain due to his stupidity/drunkenness? We also see him break bottles against his head with similar indifference and abandon.
Visible crew/equipment: Look at the blank wall just in front of D-Day when he rides his motorcycle up the stairs of the frat house - it has the most obvious boom shadow you will ever see in a film. (00:09:15)
Continuity mistake: When they show Flounder's face on the screen they throw beer cans at it and it gets soaked. When Otter gets up it is completely dry. (00:13:55)
Revealing mistake: During the scene where the Delta boys are looking at slides of the recruits from the evening, Otter steps in front of the screen to defend Flounder. Notice that he is standing directly in line with the projector to the screen and there is no shadow on the screen nor is part of the slide projected onto his chest. (00:14:10)
Continuity mistake: During the classroom scene, Donald Sutherland writes the word "Satan" on the board. In the first shot, the "t" in Satan in directly over the crease on the chalkboard. In the next shot, it is clearly on one side of the crease. (00:18:00)
Continuity mistake: In the classroom scene, Donald Sutherland takes a bite of the apple and a split second later in the next shot, he has nothing in his mouth. (00:18:05)
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)
Visible crew/equipment: During the scene where Otter is hitting golf balls at the ROTC cadets, Niedermayer is wearing a highly polished chrome helmet. In at least one shot, you can see a movie light reflected in it. (00:20:10)
Continuity mistake: When they're at the man's house who offers them some pot, you can see that he's petting a Siamese cat. But when he stands up to go put the blinds down, the cat is gone and he never moved it off his lap. (00:22:50)
Audio problem: When D-Day, Bluto and Flounder are running out of Wormer's office after the horse died, there is a sound effect of them screaming as they flee the scene. This exact same sound effect is used when the boys run out of the all-black bar, except Bluto and D-Day weren't there; it was Flounder, Kroger and Boon. (00:30:40 - 01:17:15)
Continuity mistake: In the cafeteria, Bloto puts stuff on his tray. Before the cut his bunch of bananas are on the side of the tray. After the cut the bunch is on the other side. (00:33:05)
Visible crew/equipment: In the scene just prior to the food fight, as John Belushi goes through the cafeteria line putting the food on his tray (which moves frequently), note the cameraman's feet in the mirror over the food following him. (00:33:30)
Continuity mistake: In the cafeteria scene, Kevin Bacon's character sits down twice. (00:34:05)
Continuity mistake: In the cafeteria "I'm a zit" scene, Bluto picks up the mashed potatoes with his right hand, but the very next shot shows him placing it in his mouth with his left hand. (00:34:50)
