Continuity mistake: As Ren is dancing after the confrontation with his uncle we can see him dancing through the factory. He then does some gymnastics on a bar on the loft. If you look you can see that he is wearing gymnastics grips on his hands. Yet he did not have them on in the shot before, or in the shot afterwards.
Continuity mistake: In the scene where Ren is dancing in the warehouse, he takes off his sweatshirt on the second level and throws it at his feet. His beater-T is clean then. After he jumps back down to the first level, his beater-T is dirty. Then he goes through a door and slides down the staircase and his beater-T is clean again.
Continuity mistake: During the "chicken race", there is a wide shot showing both tractors with a few meters between them. The supporters of Chuck are far away from Chuck's tractor and Ren's friends cannot be seen at all. In the next closeup showing Ren, his friends stand in the background just a few meters away from him.
Continuity mistake: When Willard and Rusty arrive at the prom, Rusty's hair is asymmetrical and completely covers her left ear. When Willard pulls her into the middle of the dance floor to show her that now he can dance, her hair is much less asymmetrical and her left ear is perfectly visible. Her hair has not became ruffled while dancing, as the party has just begun.
Continuity mistake: When Ariel is standing on both cars, from the truck driver's perspective, the trailer truck is a few meters away from a railroad crossing and the other two cars are quite near. The truck driver drives on, pulls the horn, then we cut back to Ariel. Now, the truck is far away and no railway crossing can be seen.
Continuity mistake: During the "chicken race" there is a wide shot showing both tractors with a few meters between them approaching each other very quickly. Then Ren's shoelace gets caught, he tries to jump, and Chuck jumps off his tractor several seconds later. With the speed shown in the wide shot, the two tractors would have collided in an eye-blink.
Continuity mistake: When Ariel climbs from the car into the truck, one of the wide shots shows her practically "stretched" between the two vehicles, with her fingertips and toes holding her up. In the next closeup she is back into the car down to her knees and she starts climbing out of the window again.