Continuity mistake: When the motorbike rides by, Jenny runs after it yelling "No, wait." In this shot Jenny has the flashlight in her right hand and the big red rose as part of her prom outfit is on her left breast. But the next shot is obviously flipped, as the torch is now in her left hand and the rose is on her right breast.
Continuity mistake: When Leatherface gets Heather in the house, he grabs her and drags her down the hallway, as he enters a room, Heather grabs the sides of the doorway, to pull herself away from him. In the shot, you can see the wall to the right of the doorway has a mirror on the wall, nothing else, and on the counter below is a few lone lightbulbs and a coke can. However in the next shot, so many objects appear. There's now meathooks, chains and belts hanging on the wall either side of the mirror, and the counter is now covered in canisters, metal barrels and boxes.