When Marty is attacked he is stabbed in the back by Judah Buckner - hole and blood stains clearly shown. When he is in the elevator with Dana it is clear there is no cut on his back - the shirt is whole.
When Dana first enters the cabin she leaves the door open, the film cuts to Marty standing outside where we see the door close. When the scene cuts back to Dana the others are walking in through an open door.
When Curt is on his motorcycle there is a closeup camera shot of him and his hands. The motorcycle he is riding is equipped with a twist throttle and he is clearly revving the engine using his right hand, which would be correct. However, later in the shot he is shown revving the throttle with his left hand, which would be the hand the clutch is operated with.
Bottles of beer are shown up to their necks in water in a cooler, and one bottle is shown being extracted from the cooler with water dripping from it. In the next shot when the bottle is tossed to someone, it is clearly completely dry.
When Jules is trying to having sex and open her shirt, her head is leaning right, but when the camera angle change, her head is leaning left. Also, Curt's hand is on Jules stomach, but when the camera changes, his hand is on top of Jules's thigh.