Continuity mistake: The strings of lights for the reindeer reins change continuously from one strand to two.
Continuity mistake: The position of the man on the crate after he is crushed by it changes.
Continuity mistake: When Ernest picks up the Christmas tree from the freeway, he throws the Christmas tree into his taxi. It smashes the driver-side rear window. But, when he drives away, that window is still intact.
Continuity mistake: Right after Santa Claus tells Ernest that he doesn't have money, the clothing that the girl is wearing changes.
Continuity mistake: After Ernest runs over the spike strip, the truck continues rolling, but a few seconds later it is shown sitting directly on the spike strip.
Continuity mistake: The first time we see Ernest driving the cab the passenger pats his shoulder telling him to hurry up. The passengers hand was on his shoulder when he said this but in the next shot both his hands are on his briefcase.