Continuity mistake: When the they first show the Evil Snow-Plough Man, he's chasing kids and they run off to the left side of the road as proven when the kid's sled gets crushed. However, once he's past, they all pop up from a mound of snow on the right side of the road.
Continuity mistake: When the mom comes home late for dinner near the beginning of the film she sits down but then her phone rings and Chevy Chase is seen with his wallet already out in his hands. However, in the next shot of Chevy Chase, he takes his wallet out from his coat again.
Other mistake: When the children first hit the principal with a snowball, the steak he is cooking lands onto a lawnchair. A few seconds later, his dog picks it off from the ground, and not from the chair.
Continuity mistake: When the wife gets hit with the snowball thrown by her kid, she throws her phone. If you look in the background right after that you can see the phone in plain sight laying in the snow between her and the house. A fer scenes later however it has jumped to under the tree.
Continuity mistake: During the scene where Chevy Chase is interviewing the kid at the ice sculpture festival, the position of Chevy Chase and the kid in relation to the ice sculpture change constantly and very noticeably throughout the whole scene until the ice sculpture falls.
Continuity mistake: When Snow Plough Man drives his truck around clearing snow, he honks the horn of his truck by pushing the button on the steering wheel. The sound that is made is an air horn. In reality the button on the steering wheel of a truck honks an electric horn like a car. The air horn is actuated by a rope or cable hanging from the ceiling.