Continuity mistake: When the girl shoots herself her body is still sitting upright in the backseat, but when the van hits a bump in the road and the body falls onto its side. When the van stops in the next shot the body is sitting back up again without anyone moving it.
Continuity mistake: When Erin and Pepper are trying to hotwire the van, the window is rolled down. After Erin starts the van and twists the wires together, the window is rolled up.
Continuity mistake: In the scene where the sheriff and Andy are rolling the girl up in plastic wrap, as they're lifting her out of the van, in one shot the plastic wrap completely covers her head, and in another the top of her head is exposed.
Revealing mistake: When Erin gets into to the truck, in the next shot the camera backs up a little and you can clearly see that it's only raining on the truck.
Continuity mistake: In the scene where Erin puts Andy out of his misery by stabbing him, she gets covered with blood. A scene or two later though, her shirt is clean again.
Continuity mistake: After Erin & Andy are attacked at the house, Erin runs back to the van, jumps in and attempts to start the van. When she puts the key in the ignition it is on the left side of the wheel and she uses her left hand. However, there are 2 closeup shots of her hand turning the key and the ignition is now on the right side and it is her right hand turning the key.
Other mistake: When Leatherface chops off Andy's leg with a chainsaw, Leatherface's shadow is seen through the bedsheets, and he is next to Andy. However, Andy runs by very quickly, and there is no way Leatherface would have had enough time to reach froward and chop off his leg.
Revealing mistake: When the kids are in the van and leatherface is on top with his chainsaw, you can see in one cut that the mad magazine poster/cloth on the roof is already cut, just before leatherface actually starts sawing into it.
Continuity mistake: When the group is standing outside the building where they found Jedidiah, he says that the sheriff is getting drunk. Morgan starts to say something, and his arms are by his side. The shot instantly switches to in front of him (in the middle of his sentence, so no time passes) and you can see that his arms are crossed in front of him. You can't see his hands, but you can tell by his shoulders (and the parts of his arms that you can see) that his arms are crossed. He had no time to raise his arms and cross them.
Continuity mistake: In the scene where the Sheriff is wrapping the suicide victim's body, he has a roll of plastic wrap. He is shown with the box, then as he begins to wrap the head, he has just the roll, and in the next shot it is back in the box again. He presumably would have left it out of the box the entire time, since the box would only get in the way of trying to wrap the body.
Continuity mistake: There is a shot of the girl right before she reaches into her dress and pulls out the gun. The shot is looking from her right side and you can see a lot of blood on her left leg. The shot switches to in front of her and she reaches for the gun, but there's no blood on her leg. The shot switches again, and the blood is back. This happens a few times during the scene.
Continuity mistake: After the girl shoots herself and two of the guys are arguing by the passenger side door, the front passenger door keeps changing between open and closed between shots.
Continuity mistake: Throughout the movie, the van of teens passes the Blair Meat Co. and the gas station, which are on the right side of the road. Then at the end of the movie when Erin flags down a trucker, he is heading the same direction except the meat company is now on the left side of the road. The gas station, however, is still on the right side. If they were on the same side of the street before, how could this be? They don't show either driver making any turns.
Continuity mistake: The blood stain on the rear window of the van is changing its size throughout the movie. One shot/scene, there is almost no blood around the hole, next shot/scene almost whole window is covered with blood. It happens before they have cleaned the van.
Continuity mistake: In the scene close to the end where the girl steals the sheriff's car and runs him over, you see him impacting the windshield and blood splattering on the windshield. After she hits him, she drives forward, stops, then reverses over him and right before she drives over him again, you see the windshield wipers wipe a whole bunch of untouched blood off of the windshield. The wipers had been on the whole time, they would have wiped most if not all of the blood of by then.
Revealing mistake: When Erin runs over the sheriff, she is shown bouncing around, holding onto the wheel with both hands. As she's driving away, the camera pans to the baby, who's sitting straight up on a blanket (?) with no seat belt on. Highly unlikely position after all that erratic driving.