When Ernest is fighting the foreman, at one point his hat is knocked off his head, but it is back on in the next shot.
When Ernest is driving the school buses at the beginning of the movie, the buses change back and forth from a Ford to an International Harvester Loadstar several times.
In the second ladder sequence at the end of the movie, Ernest falls with the ladder. In the next shot with him laying on the ground, the ladder is not seen. In the next shot after he has pulled down the sign, we can see the ladder was resting covering his entire body and should have been seen in the second scene.
When Ernest first meets the "second chance boys", the boy with the yellow shirt's sunglasses disappear and reappear between shots.
In the first exploding lantern sequence, the lantern has a diffuser bulb installed. When it launches into the air and crashes to the ground, the diffuser bulb has been shattered. Ernest carries it away, and in the next scene, the bulb is back in place on the lantern.
When the ladder falls over backwards with Ernest in the beginning, you can see he jumps off screen before it hits the ground. You also see that he wasn't very high off the ground. Maybe 3-4 feet.
When the second chance boys unravel the gauze on Ernest with the bus, a section is pulled taut in front of a group of them; however, it remains stationary as the bus is supposed to be pulling it.
When Bronk Stinson bullies "Moose" Moustafa, you can tell his voice is added in later when he shouts, "No!" to the foreman.
Bronk Stinson's laughter is added in later while his back is turned to the camera. When operating the bulldozer to destroy Camp Kickakee's cabins, Lyle Alzado isn't moving as he "laughs".
During the poker game we see a shot of the woods and the cabin, and a crew member in a blue shirt can be seen standing in the woods.