Continuity mistake: After Gerry gets smacked in the face by the 'broken' suspender clasp, we see the silver clasp land under the dresser. Yet, when he's moaning and lifting his leg to get onto the bed, we can actually see the clasp still intact on the front suspender that came loose, which is dangling right behind him (just look between his legs). Of course, in the next shot, that clasp is gone. Since the silver clasp is one of the plot points, this is bizarre to say the least. (00:11:10)
Factual error: It is not possible to be "allergic to all known anaesthetics". Amongst the amide local anesthetics lidocaine, prilocaine, bupivicaine, mepivacaine and dibucaine are naturally occurring substances and if administered without a preservative they cannot trigger an allergic reaction. If Bales is allergic to them, he'd be allergic to the metabolic processes of his own body. They are all powerful local anaesthetics and could easily be used for a radical rhinoplasty such as that required by Bales.
Continuity mistake: In the bedroom scene the girl is holding a clear cup full of beer. The camera goes off her and when it comes back she is holding a blue cup. The camera goes back off her then on her and the cup is clear again. [This mistake does not appear in the unrated version - the blue cup scenes were shot specifically to secure an R rating from the MPAA because the contents are obscured.]. (00:13:20)
Continuity mistake: If you look carefully at the monster (Frankenstein) you will see that his face is different in the ending scenes. The reason is, during the movie you see the monster take the woman doctor and throw her out the laboratory window. You then see the monster kind of stumble, which he really did and broke his ankle. So in the final scenes they replaced Lon Chaney Jr. as wolfman with a stuntman, and Lon Chaney Jr. finished the movie as the monster.
Revealing mistake: When Carl is being dragged away by the demons, you can see the cable line that he's attached to. May be fixed on DVD.
Visible crew/equipment: After Josh tells Cher she's such a brat, at the start of the next shot which is the first close-up of Cher during the driver's test, just as she says, "I had an overwhelming sense of ickiness, even though I apologized to Lucy," the top of a crewmember's head, with his short wavy hair blowing in the wind, is reflected at the bottom of the Jeep's windshield, directly in front of Cher and the steering wheel. (01:11:55)
Continuity mistake: When Uma Thurman visits the radio station for the first time, she asks Janeane Garofalo if she can sit down by the microphone. As she's standing in front of the desk she's wearing a cardigan with a handbag over her shoulder. When she turns round to say "you promise not to laugh?", the cardigan and bag have disappeared. (00:16:10)
Continuity mistake: During the Xmas day scene, Markus receives a Sony portable CD player as a gift from Will. However, before the gift's unwrapped, the Sony box is visible on the table. (00:51:45)
Continuity mistake: When the real 'manager' comes outside to yell at "Mr. O'Donnell', you see the manager walk back into the club. If you look in the background of the next shot, you can see the manager walking through the door again. (00:13:25)
Continuity mistake: In the beginning of the movie he is not taken onto the hockey team. After he is hustling at the driving range he goes to toughen up. As he is toughening up, Chubbs unplugs the machine. The kid tries it, but he never plugged it back in and the machine still manages to work. (00:15:10)
Other mistake: After the great fire scene there is a raccoon that drags her baby to shore and begins cleaning it. A few seconds later the baby has jumped across to the other side of his father and siblings, but the mother does not stop licking.