Continuity mistake: Luke McNamara is handcuffed behind his back at the police station but as he is loaded in to the ambulance he mysteriously is cuffed in front. [The handcuffs inside are normal police issue handcuffs and outside as he's getting into the ambulance they're attached to a belt, normally used for criminals they consider dangerous.]
Continuity mistake: After Luke's returns from his first Skulls adventure, he goes to his friend's apartment and throws himself onto the couch and pulls a pillow out from beneath himself. From another camera angle he pulls the pillow out again.
Continuity mistake: During the rowing scene when everyone is racing, the camera goes out to a long shot of all the rowboats and you can see one of the film crew lying down in one of the boats. It can't be the cox - in an eight (which is being used here) coxes can only be seated at the back of the boat. It is considered too dangerous to make an eight a 'front end loader' as he is not as aware of his surroundings.
Continuity mistake: When Lucas is being handcuffed every time it switches shots different police are holding him.
Continuity mistake: The size of the stain on Luke McNamara's T-shirt changes considerably after he swigs from the trophy from small to large.
Factual error: Placing a watch over a fresh brand would hurt a lot and they would be adjusting their watches continuously because of the gross scabbing.
Continuity mistake: When Oxford and Cambridge are racing, one of the gates(oarlocks) visibly snaps. Yet in the next scene, the gate has been mysteriously repaired to its former condition.
Deliberate mistake: In the scene with all the coffins and new Skull "recruits", Lucas knocks on the unopened coffin and Caleb pops up. The next shot is a wider shot that shows everyone standing around Caleb's coffin, but the guy in the coffin is not the actor playing Caleb, but a stand-in.
Continuity mistake: In the boat race in certain shots the scenery behind Luke McNamara's boat changes completely, as well as the number of boats that are around them.
Plot hole: Wouldn't the other secret societies be expecting the Skulls to try to steal their mascot? After all, they claim they have stolen every one but the one they steal in the movie. So that one must know they are next. Yet these Skull wannabes all very noisily and clumsily manage to get the weathervane without any problem. It is hard to believe a secret society would be so easily robbed, especially if they had SOME inclination that the attempt would be made.
Plot hole: A true secret society of that calibre would never allow itself to be known to the point that a perspective pledge would know the deadline for when his last chance would be to become a member.
Other mistake: When Caleb and Luke are stealing the snake weather vane, when they fall into the moat, you can see the snake floating. This weather vane is presumably made out of metal and should sink like a rock but you can see it floating when they fall.