Continuity mistake: When the reindeer gets into the house and runs around, it knocks over a TV set. All of the magazines that are on top of the set come crashing to the ground, including a TV Guide with "Get Ready For A Fabulous February" (or something like that) in big letters on the cover. Interesting since the movie is set around Christmas time.
Continuity mistake: When Jessica sits on Santa's lap in the department store, and asks for the real Santa's help to assist Prancer, she pulls down Santa's beard a bit. In one shot, the beard is definitely below his nose, after it is pulled. In another shot, the beard is right up under his nose. There are various shots where the beard is up one second and down the next.
Continuity mistake: When Jessica goes to the barn to investigate the banging, her hair is stringing in her face in one shot, and then in the next, it's brushed to both sides of her face.
Continuity mistake: Near the end, when Jessica and her father are taking Prancer to the mountain, within the three shots that it takes to show Prancer getting off the truck, walking around, and running away, he has his bells and bridle on, then off, then on again.
Continuity mistake: When Jessica comes out to their barn to investigate the noise, in one view, her hair is all brushed out of her face. Then the view changes, and her hair is in her eyes. Next view, the hair is brushed away again.
Continuity mistake: When John Riggs is reading the newspaper while Prancer walks past outside, he first reads the main section, then puts it down and picks up the sports. But later, he puts down the main section and picks up the Community Section.
Continuity mistake: The people at the church already have their candles lit in the first scenes, but they light them again.
Continuity mistake: The sky changes several times during the sledding sequence. It's sunny and then overcast.
Continuity mistake: After the news reporter starts writing, there are shots of the paper being delivered. One is of Cloris Leachman's house. Notice that the Christmas star on her roof, just put on minutes before this, is now missing.
Continuity mistake: When Sam Elliot is reading his newspaper, and Prancer can be seen in the background, it's snowing in one window but not the next. Then it's sunny, then snowing again.