Other mistake: When Mitch, Frank, and Beanie decide that they are going to have a party they say the party is on a Friday night. When they show the outside of Mitch's house you see the sign for the party and it says the party is on Thursday at 9:00. Then when Frank talks to the guys with the beer bong he says that tomorrow he has a nice Saturday planned. If the sign is right then he would have a pretty nice Friday.
Plot hole: When they are being told they have failed the evaluation, the dean tells them, "Yes, you people did finish with 84%, but another one of your pledges finished with a zero in every category." It then goes on to state that this drops them down to 58%. For one pledge to bring them down 26% there would have to have been less than four pledges, including Blue, i.e. only three actually taking the evaluation.
Continuity mistake: When Dean Pritchard is telling the frat guys that they failed, he flips up the first page on his clipboard. While the paper is flipped up, we can see that there is a line drawn through Blue's name. When he flips the paper back down, Blue's name is no longer crossed out.
Continuity mistake: When Will Ferrell is in the living room for the first time, there are two hockey sticks leaning there. One stick has just a stripe of tape on the blade and the other is mostly taped. He is first holding the one with the mostly taped blade and later it shows him with the other hockey stick.
Continuity mistake: When Spanish is running away from the van when the guys are trying to kidnap him, he goes from having his backpack on, to not having it on. Then when Frank tackles him in the fountain, he has the backpack on again.
Continuity mistake: When Frank is seen streaking down the street, there is a brunette in the back of his wife's vehicle and she is wearing a hat, but in the end of the scene after Frank has sat beside her the hat disappears between cuts.
Continuity mistake: When Frank shoots himself in the neck with the dart gun, we see him fall over a table as his sandal falls off his right foot, but in the next shot his sandal is back on his foot.
Continuity mistake: At the wedding, the coffee stain on Nicole's dress is low and to her right in some shots, while it is high and to her left in other shots.
Revealing mistake: When the b.j. instructor gives Frank the black eye, Frank has a bandage on his neck where the dart will strike.
Revealing mistake: When Frank shoots himself with the trank gun you can see that he is wearing a prosthetic neck piece with the dart in it.
Continuity mistake: When Frank falls over the table after shooting himself with the dart gun, there is a straw hat on the chair. The hat sticks under his right arm. But in the next shot, it is away from his arm and visible in front of the camera.
Other mistake: In the movie, Beanie describes Blue as "an old Navy vet," (meaning Veteran) but in the German subtitles, Beanie describes Blue as a Marine Veterinarian (tierartzt). Funny.