Continuity mistake: When the "old man" first puts the lamp on the edge of the box there is no light fixture on which to place the shade. He then returns the lamp to the box and when he brings it out, there is a place to put the shade. Also as he hands it to the mother and then takes it back to put it on the table, there is no electrical cord visible. However, just before he sets it down on the table you can see a cord in his left hand.
Continuity mistake: When the father comes in for hot water for the car, the furnace goes haywire and black smoke comes out of the register. The father goes to the basement to fix the furnace and yells upstairs for somebody to open the damper. The mother goes over and begins to move the bottom lever and then changes her mind and moves the top lever all the way to the left. In the next shot the top lever is all the way to the right while the bottom lever has miraculously moved all the way to the left.
Continuity mistake: In the kitchen scene, as Ralphie's father comes in for hot water to thaw the car, and then turns his attention to the furnace, there is a white funnel on the shelf beneath the clock. The camera follows him to the basement steps and the smoke coming from the register. In the next shot, showing the anxious family, Ralphie's mother moves forward and the funnel has moved to the sink behind Ralphie's head.
Continuity mistake: Early in the movie when Ralphie catches up with Flick on the way to school, Ralphie is holding a book or folder that has the top left corner folded over. In the next shot when Schwartz joins them, the fold is now on the bottom left side. Ralphie's arm covers the top corner of the book most of the time so look closely during the last few seconds of the scene.
Continuity mistake: In the playground scene when Flick first sticks his tongue to the flagpole, the street in the background has been snowplowed. The kids all go back in to the classroom without Flick. When the teacher asks "Where's Flick?", and looks out the window and sees him at the pole, the same street in the back ground has not been plowed.
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: 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)
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.