Revealing mistake: When Cindy and Buddy get trapped inside the cold chamber, she starts rubbing him to a point that it becomes masturbation. But when she's sitting on his legs doing the thing, in one side shot you can clearly see she is not holding his privates and her hand is just going up and down, closed but empty. (00:58:05)
Revealing mistake: The kid in the wheelchair is playing a Game Gear with no game in it.
Character mistake: When Missy is at her audition, Courtney and Whitney get annoyed and tell her to do a sequence, (front handspring stepout, roundoff back handspring stepout, roundoff back handspring, full twisting layout). However, when Missy starts the sequence, she starts with a cartwheel instead of a front handspring.
Visible crew/equipment: At the party towards the end, Sherman leaves and Carla comes after him. As she runs toward him, the battery pack slides down her leg.
Continuity mistake: As the hand creature busts the shackles off Boris' legs in Lunar Max, you can see the bottoms of his pants over his metal prison boots. There are only a few folds and wrinkles over his left foot, and the pants over right foot are hardly wrinkled at all, or affected as the creature climbs up his right leg. But only a couple of seconds later, we see another shot of Boris' feet as the creature breaks off the metal sleeve of his arm, and suddenly his pants legs are very wrinkled. Boris was standing perfectly still the entire time. Boris' legs are also suddenly closer together. (00:03:35)
Continuity mistake: When Frankie is fighting Mitch and gets thrown off the balcony the diaper bin on his head comes off, but in the next shot when he lands in the pool it's back on his head.
Revealing mistake: When they get back from Bunyans and the garbage is on the floor, Chet runs to the bathroom. The family and Roman follow him, you see Dan do a 3 count for everyone to run back In screaming, the blocking of that shot included a gap that you could see them off camera right.
Revealing mistake: When The Mask is dancing with Tina and he turns her into a human tornado while spinning her around, none of the onlookers in the crowd show the slightest bit of amazement at the impossible feat that just occurred in front of them, indicating that the extras were not directed to react to the special effects.
Other mistake: Even though it is snowing throughout much of the movie, none of the snow seems to stick to any of the characters' fur. Even during the fight scene when they are rolling around in it, they are never covered with white.
Visible crew/equipment: When a gremlin attacks the Mum from a Christmas tree, and the tree falls on top of her, you can clearly see a member of the crew with eyeglasses, wearing a red shirt, standing behind the tree pushing it forward on top of her. (00:54:30)
Other mistake: The envelope with the letter for Amanda is suddenly in a very good condition as it ends up in the peanut bowl... even though it has been in the trash, had chewing gum attached to it, been trodden on, had a beer barrel rolled over it, etc....