When Fritz is attempting to fix Winston's Volkswagen Beetle after it's broken down in the desert, he opens the hood. Since it's a Beetle and the engine is located in the back of the car, he goes around to the back but leaves the hood up. Throughout the rest of the scene, the hood alternates from either being up or down.
When he emerges from the trash can, Fritz's outfit changes color from red to blue to red again between shots.
When Duke and Fritz leave the bar, the knife on the floor disappears.
When the two pig cops are reintroduced, Ralph is shown to be wearing brown shoes. This is jarring in and of itself, since Pig Cop #1 is not wearing any shoes. The shoes disappear in the next scene when Ralph gets hit by the car.
During the scene when Winston and Fritz are out in the desert, Winston's shirt color consistently changes from being light red to being dark purple, during the entire scene.