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 the frat throws Blue a KY wrestling match, they have several matches before it's Blue's turn. However, when they show Blue and the two girls in the kiddie pool, the pool looks like it has never been used - there is no KY on the sides. There is no way they could've cleaned it all up, and I doubt they had a separate pool lying around just for him.