When the kid gets hit in the forehead with the bottle, his black eye and other facial injuries briefly disappear, then reappear.
The wreckage of the skateboard ramp in the street changes.
When Gord's dad wakes up in Pakistan he has a full beard but minutes later when he and Gord are lay on the desert floor he has a box beard.
The toilet paper in the scuba gear scene changes between shots.
When Davidson throws the cartoons at Gord, Gord drops some, but when Davidson's car pulls away, Gord is holding all of the papers.
Sexually abused children or even adults do not go to institutions in real life. Their abuser would go to jail/prison. When Gord falsely accuses his father of fingering Freddy. Freddy ends up going to an institution for sexually abused kids despite being an adult and when the psychiatrist and the cop refused to listen to Freddy and take him away. If the accusations were true, Jim would most likely be arrested and charged. And even though it's false. Gord would've most likely got arrested for making a false report.
Gord could get arrested for impersonating a doctor.
Jim would've got arrested for assaulting Darren outside the bank especially kicking him in his injured leg.
When Gordon gets hit by the bus, a foot falls off the dummy's body.
The "jewels" Gordy gives Betty are obviously just colored glass; they do not refract light in the way real jewels do.
When Gorde's dad gets out of his truck, the cameraman and a few crewmembers are reflected in the side of the truck.
In the restaurant scene, Gord never gives his name to Mr. Davidson, yet Mr. Davidson then addresses him as Gord despite not knowing his name yet.
Good tells his parents he wants to go to Hollywood to become a famous animator "like Charles Schultz". Charles Schultz was a cartoonist, not an animator.
When Darren was forced to tell Jim where Gord has gone. Darren tells him that Gord is in Hollywood selling his cartoons. How does Darren know where Gord was?
Gord would've been easily fired from the cheese sandwich factory for creating a scene and the submarine sandwich shop for creating a scene with a customer.