Continuity mistake: As Brenda leaves the table asking "Does anyone need anything?", we see Bobby sitting by the table. When it cuts Bobby suddenly got something between his lips which weren't there before.
Continuity mistake: At the end, when Doug fights with Lizard, Lizard hits Doug in the face in one shot, and Doug's glasses fly off, onto the floor. In the next facial shot of Doug, his glasses are back on. (01:34:20)
Continuity mistake: When Ethel, Lynne, Brenda and Bobby are sitting around the table outside the caravan, talking, the position of the juice pitcher, ketchup bottle and mustard bottle constantly changes. (00:27:30)
Continuity mistake: When Doug is fixing the system in the camper van while Lynn is speaking to him, he lowers his arms down from the system. Then as Lynn walks over to him, holding baby Catherine, his arms are instantly back up, tampering with the system again. (00:09:40)
Continuity mistake: When Brenda is talking about having "the chronic", Bobby says "Who smokes pot?" As Bobby comes out we see Brenda with both her arms down. As it cuts she is suddenly drinking from her glass.
Continuity mistake: When the gas station attendant is sitting at the table going through the bag, he has a cigar in his mouth, but it is not smoking. In the next shot it is instantly smoking heavily. Then, in the next shot, instantly, the cigar vanishes from his mouth altogether. (00:07:50)
Continuity mistake: Ethel's nightdress has a blue dotted design on it, visible when Lizard shoots her in the caravan. Later in the movie when she is being eaten by another mutant, her nightdress is solid white. (00:56:50 - 01:31:40)
Continuity mistake: At the start, one of the mutants swings a pickaxe into the back of the head of one of the researchers and it goes through their helmet. In the next shot when he hits the floor there is no hole. (00:01:45)
Continuity mistake: When Brenda saturates the tire with lighter fluid, right before she lights it, it turns to burn gel.
Continuity mistake: At the very end of the movie, when Doug returns with the dog and the baby, the survivors have a big hug. Then the camera pans out and we discover someone is watching them. When the camera pans out there is absolutely no sign of the trailer that just blew up or the car.
Continuity mistake: When Lynn is retrieving the dog from inside the gas station attendants room, the dog messes up the window blinds. Between shots the position of the blinds in front of the window change, as Lynn turns around and is startled by the attendant. (00:14:05)
Continuity mistake: Soon after the car crash in the desert, the mom is seen bringing out deck chairs. She brings out two (one dark blue one and one light blue one) and leans them up against the campervan. But in the next shot the light blue one which was in front of the dark blue one has vanished. (00:22:25)
Continuity mistake: When the gas station attendant returns to his house, he finds a bag sitting on the porch. After he goes back inside, between shots the position of the bag completely changes. (00:07:35)
Continuity mistake: At the beginning when Big Bob and his family are first shown, at the gas station, their suburban has BF Goodrich all terrain tires mounted on chrome wagon wheel rims, after that first shot the tires and wheels change to Bridgestone Duelers on silver bullet hole wheels.
Continuity mistake: When Doug is walking across the desert, soon before he and Bob leave for help, he walks into shot with Brenda in the background laying back on her lounger and the bottle of lotion is lying on the ground beside her. In the next closeup the bottle of lotion is suddenly standing upright, beside her lounger. (00:23:40)
Continuity mistake: When Lynn walks into the gas station attendants room, she briefly lifts up the flap of the bag sitting on the table, and it falls back down. In the next shot of it when the attendants enters, the bag is opened wider and differently. (00:13:55)
Continuity mistake: When Doug goes to rescue his baby daughter from the kidnapper's bed, he creeps past the living room to see a bald matron watching TV and combing a wig. Then after he grabs his baby, and creeps past the living room, the bald matron is still sitting and combing the wig. But 5-seconds later, when he gets a few feet down the same hallway, that matron suddenly appears out of nowhere and attacks him.
Continuity mistake: In the shot where Doug's fingers are cut off, the severed finger that remains on the floor is covered in blood, but next shot of him pulling his hand away shows almost no blood on the severed finger.
Continuity mistake: The scene where the father has gone back to the gas station to look for help, he purchases a bottle of water and pays for it. He takes a sip and walks into the back. He puts the bottle down on the table, and the bottle is now half empty.
Continuity mistake: In the scene where Doug is standing by the generator and finds his baby, he hides from Cyst against the house's wall as Cyst passes, dragging a corpse. After Cyst passes, Beast whines which makes Cyst turn. In that split-second, Doug and Beast manage to get inside the rusty car a couple of feet away.
Answer: Pluto puts his hand over Brenda's mouth and Ethel doesn't bother to look over.