During the last supper, the green bottle gets emptied by the "left wingers" then when they are shown from different camera angles it's full again, then empty, then full, then empty again.
When the group is arguing after Luc stabs the girl who hates Catcher In the Rye, the victim is supposed to be dead with a knife in her back, slumped over the chair, but she can clearly be seen breathing.
The sheriff finds Pete's car with the shotgun laying on the backseat. She doesn't charge him with a crime since he has a "license". No license or permit is required to own or transport a shotgun in Iowa. However, it is illegal to transport one without it being locked in a case or disassembled.