National Lampoon's Christmas Vacation (1989)

Continuity mistake: The christmas tree is visible from the dining room, but when Lewis goes beside it to smoke a cigar, you can't see him. When the tree is on fire, you don't see Lewis again and you can only see a branch of the tree.

Revealing mistake: When Clark starts to set up his Christmas lights, there is a scene where the ladder collapses. If you look closely you can see the wire coming out from under his jacket to keep him from falling forward. (00:20:55)

Continuity mistake: When the squirrel jumps out of the tree and the whole family is hiding around the corner in the front entry, the camera alternates shots frequently from the front of the family to the back of the family. Each time the angle changes, Catherine's stance changes from her arm being around Russ to her arm at her side.

Continuity mistake: Less than a day after the ice breaks the neighbors' window, it has fixed itself in the outside shots as Clark is stuck in the attic.

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Continuity mistake: The retractable attic staircase is a type held closed only by light spring pressure, not a latch, but it doesn't budge when Clark jumps on it. When he initially opened it, and later when his wife does the same, it opens normally with a light tug from below on the cord.

Continuity mistake: When the squirrel is being chased by Eddie's dog, it passes through the broken door and then vanishes. (01:22:07)

Revealing mistake: When the neighbors fall onto the floor of their bedroom when Clark's Christmas lights finally go on, you can tell a stunt double is standing in for the female neighbor as she falls down at the foot of the bed.

Revealing mistake: When Clark is outside at night rigging up the lights, it seems as though the moon is a little too large in the sky. (00:29:35)

Continuity mistake: When Clark falls off the roof, the staple gun goes down before him. In the next shot, it's not heading down from his point of view.

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Revealing mistake: When Lewis's coat catches on fire after the Christmas tree explodes, the square on his coat that holds the "fire" is evident.

Continuity mistake: After Mr. Shirley tells Clark he will get a bonus plus twenty percent, Catherine, Rocky, and Ruby Sue cheer and get up from the couch to mingle with the relatives while Rusty and Audrey respond excitedly. There is a close up reaction shot of Clark as he begins falling, then a long shot of Clark falling to the floor as Catherine, Rocky, Ruby Sue, Audrey and Rusty are in their original positions on the couch, calmly watching Clark fall.

Revealing mistake: When Clark notices that Lewis has caught on fire, he's only burning when he pushes him on the ground.

Other mistake: After we see the cat pulling on the strand of white Christmas tree lights, there is a close up shot of the electrical outlet with one cord plugged into it. When the lights go off, both the colored and the white lights go out at the same time. Clark has to plug in two cords to make both sets of lights come back on. Either the colored lights should have been out to begin with, or both strands of lights should have come on with one plug. (01:09:05)

Continuity mistake: When Clarke is installing the Christmas lights, the rope on the ladder keeps appearing and disappearing. (00:23:00)

Visible crew/equipment: After the cat is electrocuted and begins smoking underneath the chair, the next camera angle still has the smoke machine in the shot next to the chair.

Continuity mistake: When Todd, the snob neighbor, falls down the stairs, his wife Margot is not visible in the bedroom. (00:38:55)

Revealing mistake: At the beginning of the movie, despite the fact that Clark hits the accelerator and the car goes really fast, the background shows the car is going at a normal speed. (00:04:45)

Revealing mistake: When Clark falls from the top of his house, he grabs the gutter. It bends and a icicle is thrown from it to his neighbor's house. You can see the thread which guides it. (00:24:27)

Audio problem: When Ellen cuts a head of cabbage in half after her mother asks her if she's smoking again, the sound of the knife hitting the cutting board is heard before the knife hits the cabbage. (00:23:15)

Factual error: Prior to the cat being electrocuted, Clark is seen plugging the lights into a 110 volt outlet. However, when Rusty resets the breaker, it is a double pull breaker that is reset, which typically provides 220 volts, and the breaker is off instead of tripped. (01:09:00)