Continuity mistake: During dinner Randy has been eating like a "piggie" and his face is covered with food, when the doorbell rings. As he gets up to answer the door he looks to left and his face is clean but then as they go to the door there are mashed potatoes on his face again.
Continuity mistake: When Santa pushes Ralphie down the slide with his foot, Santa is actually seated too far away from the slide for his foot to have reached Ralphie's face. In all the wide shots of the scene (especially the very last one as the family leaves the store), you can see that Santa's chair is placed too far away from the entrance of the slide for his foot to have reached the sizable distance to Ralphie's face. But in the tighter P.O.V. shots where Santa is talking to Ralphie just before he gives him the boot, you can see that Santa's chair has been moved over and placed directly in front of the slide so that he can easily reach Ralphie's face. Even better, just as the Elf places Ralphie in Santa's lap, there is a 360 degree panoramic shot that shows just how far away the slide is from Santa's foot.
Continuity mistake: Looking out the classroom window, in the scene where the teacher has gone out to help free Flick's tongue from the flagpole, we see the fire truck has arrived and that a police car has just pulled in from the left and has stopped. The shot changes to show Ralphie saying "Oh no," and then another closer shot from outside, during which the police car is again pulling up at the very same spot. (00:19:05)
Continuity mistake: When everyone is shown in a close up as they open up their Christmas presents, take a look at the father. While he is opening his gift, he has a yellow tie around his neck. When he says, "Didn't I get a tie this year?" the tie is not around his neck anymore.
Continuity mistake: Near the beginning, when Ralphie runs from his house to catch up to Flick, on the way to school, notice that Flick is carrying a school book, which has a beige cover visible to the camera. In the next shot Schwartz joins the group from the very next house on the block, and within a time span of approximately two seconds, Flick's book cover has become blue in color. (00:13:50)
Other mistake: When Pierre Andre is giving the members of the "Secret Society" their message, listen carefully. The first number is 12. Towards the end of the message he says 12 again. Since the first letter of the first word is "B", and there are no other "B's" in the entire message, I guess this is another one that slipped by the editor. They also say to set pins to B2, so 12 can't be B.
Continuity mistake: When the teacher collects all the fake buck teeth from the entire class in one hand, there is no way she can hold all twenty sets of teeth in one hand as we're expected to believe. (20 because there are four rows of five desks in the classroom.) She also doesn't deposit anywhere near twenty sets of teeth when we see her hand pour them in the desk drawer.
Other mistake: When the leg lamp is set up and turned on, the entire leg lights up. Trouble is, when you first see it, you can see there is no light in it, nor a fixture. Later, after it is broken, you again see no lighting of any kind in the leg. I don't think the light from its position on top of the leg would have illuminated the leg all the way down to the shoe at the bottom.
Continuity mistake: When Randy shows Mommy "how the piggies eat", the shots are obviously out of sequence. There are times when the amount of mashed potatoes on the plate greatly increases from the shot before. And watch the meat loaf a couple shots just before the scene ends. Three large pieces of meat loaf lie scattered on Randy's place mat, but they instantly disappear in the next wide shot.
Factual error: This film takes place in the mid-to-late 40s. The doorknobs throughout Ralphie's house are too modern for the type of doorknobs used in homes built in that era. This is especially obvious in the kitchen scene when the furnace is smoking and you see the cellar door and in the bathroom scene, when Ralphie is decoding the "secret" message from Pierre Andre. No bathroom door of that era would have a doorknob like the one shown in the film.