When Shawn and Gus are hiding in the dorm room closet while the thugs search the room, the position of the closet bi-fold doors changes. When looking at the closet from the front, the bi-fold doors on the left that Shawn is hiding behind is folded over, thus leaving a big space in the middle. When looking from Shawn's point of view, the bi-fold doors are spread, closing the closet door completely.
When Shawn and Gus enter the closet to hide, the door slats are closed. When they are looking out at the bad guys, the slats are open. When they exit the closet a few moments later, the slats are closed again.
As Gus and Shawn are leaving, Shawn grabs the fully popped popcorn bag. The microwave never indicated was done and no one ever removed the popcorn from the microwave.
When Lassiter plays with the prop gun, he pauses holding it at shoulder height. In the next shot, of him from behind, he holds it much lower.
When Shawn is talking on the police radio using the hand held microphone, he correctly depresses the push-to-talk switch to speak. Immediately thereafter, he gets a response. However, when the response comes, Shawn still has the microphone switch depressed. These are "Simplex" devices, meaning only one party can speak while the other listens, as opposed to "Duplex" (like a telephone), where both parties can speak and listen at the same time.
The rear view mirror is missing from Buzz's police car.
Shawn and Gus gets donuts from a Dunkin Donuts station at Bazo's Grocery. However Dunkin Donuts did not exist in California at the time.