Audio problem: In the scene where the janitor is tap dancing in the hallway, the tapping sounds do not match up with the times that his feet hit the ground.
Continuity mistake: When Joe is being thrown during the fight scene, You can see it's not David Spade, but the stunt guy.
Revealing mistake: When the cop drops off Brandy's dad and it first shows him with no leg, you can see his real leg behind him.
Continuity mistake: In the scene just after Joe finds his parents, when they are sitting in their trailer talking, his parents have a stuffed clown between them. Just before Joe asks them if there ever was a time when they'd be staring at the moon, the clown is slumped forward with its face not visible. In the next shot, when his mom starts her sales pitch about having clowns for sale, the clown is now standing upright between them.
Continuity mistake: The 8-track has name on front in the beginning, Then when Joe turns it down to show I.D, Its a completely different 8-track. But the same song is playing.
Continuity mistake: When Joe is left at the Grand Canyon by his parents, he is wearing a green "Life is a garden, dig it" T-shirt, but when he is strolling down the path at the Grand Canyon (you can see it behind him) he is wearing a plain white shirt.
Continuity mistake: When Clem stops dancing and starts talking to the fire extinguisher, he throws the duster broom handle down, which is in the same direction as the duster. Then when he asks question, "Does your mother sew?" the handle of duster is now sticking out the wrong way.
Continuity mistake: When Joe spins the tires for the security guy, The tire that's supposed to be spinning is on the left side. But after Joe says "does this look like a piece of crap to you?" It shows the right side spinning on close up 3 times, But when they show a wide shot of the car the right side is not spinning at all and the rubber burns are on the left side of the car.
Continuity mistake: When Joe is on the bridge and before he starts talking to Brandy, in some shots his boots are facing away from her, but in others you see him turned towards her.
Continuity mistake: When Joe peels out and the security arm goes down it is split near the lower part by the gear box. Then when security guy kisses the arm, the split is gone. Use slow mo and you can see it.
Continuity mistake: When Joe starts to hold up the picture of his parents butts, on the right side of the podium you see grass on the microphone. When Joe asks if any one has any info, the grass is gone. It happens a couple of times during the interview.
Continuity mistake: In the scene where Joe sticks his head into the aligator's mouth, while he is explaining the 3 rules, his cigarette changes hands from one shot to the next.
Revealing mistake: After Joe blows up the A-Bomb, the film is reversed for a second as is evident by Joe's "I Choked Linda Lovelace" shirt.
Continuity mistake: In the scene where Joe sees the "dead" janitor, he goes under the police tape twice (once when he is talking to the police officer about the death, then again when he goes to say goodbye to the janitor.)
Continuity mistake: At the end of the movie in the scene with Joe and his parents, after Joe leaves the trailer, his dad has a beer in his left hand, then not, then again, then not.
Continuity mistake: Near the end of the movie Joe wakes up at Brandi's house and they run out to find Joe's "hemi" sitting in front of the house. The camera shot shows the car from the right side, and you can see the rear-view mirror attached to the windshield. And shortly afterward when they all get in Joe's car, another camera angle shows the mirror as well. But when they're speeding away from the house the camera angle from the front of the car shows the mirror is no longer there.
Continuity mistake: When Brandy's dad has his foot stuck in the railroad tracks, from shot to shot he goes from being on the inside of the tracks, to the outside. Sometimes he's standing on the wood planks and other times he isn't.
Other mistake: When the old man gets his foot caught in the railroad switch, the switch closes on his foot, trapping him. As the camera pans out we see that this was not an electric switch but a hand throw switch, meaning that someone had to be standing at the switch manually operating it to close on the old guy's foot.