Continuity mistake: When Howard is first talking to the Santa in the department store the Santa tells him to "Have a little respect for the suit" then part of it slides off like it was glued on. He then sticks it on again. Problem is, when they are fighting at the conmen's hideout, he takes him down by pulling his beard - that is now held on by an elastic cord and snapping it back. Granted it is not the same scene, however the only thing that happened between these two shots is them driving to the hideout and he would have had no reason to change it.
Factual error: When Howie's (Arnie) vehicle breaks down, he's on a landmark bridge in Minneapolis, crossing the Mississippi River at Nicollet Island. He's at essentially Zero Hennepin Avenue, Minneapolis, as the river is the dividing line between East and West Hennepin. He pushes the car off the end of the bridge and rolls to a stop at a diner. This is the landmark Mickey's Diner in downtown Saint Paul, some ten miles away, the one located at 36 Seventh Street West. Howie should have looked even more exhausted than he appears in the film.
Continuity mistake: In the scene, when Liz (Rita Wilson) is making cookies, Ted (Phil Hartman) comes in. In the shot, when she is scooping the cookies off the baking tray onto the plate, she only has 1 on the plate. The camera then goes to Ted, and in the next shot, nearly all of the cookies are on the plate. How could she have done that so quickly? They were so neatly arranged on the plate, and none were broken.
Continuity mistake: In the scene where Howard is in Ted's house stealing the Turbo Man doll, and he catches the wiseman on fire, we see a shot of carollers outside. The ground is covered in snow and the sky is overcast. Howard then kicks the wiseman's fiery head out the door in the direction of the carollers, and the carollers scream and run away. It is now sunny outside and most of the snow is melted.
Continuity mistake: At the end of his jetpack flight, Howie is diving headfirst straight down towards the ground. Then when the camera changes shot to see his landing, he hits the ground at a completely different angle, on his back. Furthermore, he suffers no injuries - that costume must be very well padded.
Continuity mistake: At the part where Howie is in the neighbours' house "stealing" the Turbo Man the head of a statue catches on fire. He tries a couple of times to get the fire out. In one shot the head is right next to his foot and in the next shot the head is gone. Then in the very next shot the head is back and he kicks it out the window.
Continuity mistake: During the parade you can clearly see trees in the background with plenty of green leaves.