Revealing mistake: After the squirrel lands on the coffee table, it rises up and twitches its tail in a mechanical motion, showing it is really a puppet.
Continuity mistake: As the shots quickly change from the front of Catherine and Rusty to their backs, Catherine is either holding Rusty tightly to her, loosely, or not at all.
Continuity mistake: When Uncle Lewis and Aunt Bethany arrive, the wreath on the front door is lit with Christmas lights. When the door opens from inside the home, there are no lights on the wreath....it is just plain green. (01:01:58)
Continuity mistake: When Clark and Eddie are standing next to the Christmas tree drinking eggnog, when Eddie walks over to the decoration and knocks it over, in one shot his glass is less than half full and in the next it is almost completely full and he takes a gulp. (00:45:55)
Continuity mistake: When Clark is sliding down the hill on the sled, several times you can see fins on the bottom to help whoever was riding it control the direction a little better. When Clark is rubbing the oil on the bottom of the sled before he starts it is completely flat on the bottom. (00:50:28)
Visible crew/equipment: Just before Clark goes down the hill on the saucer sled you see the view down the hill. If you look carefully at the right of the screen you can see two pinkish cables stretch into the distance. These are the pyrotechnics that make the explosions Clark sets off. You can see it clearly on the DVD version, but not too clearly in the VHS one. (00:50:15)
Continuity mistake: After Eddie et al arrive at the Griswolds, "Snots" is introduced. When everyone else has gone into the house, Clark is left outside with the dog. A shot shows the dog at Clark's side, and if you look at Clark's sleeve, he's wearing a sweater, but actually has on a windbreaker. At the end of the movie, Clark's wearing the sweater. Apparently the shot was taken of him and the dog, and edited back into the film early on. (00:44:30)
Visible crew/equipment: When Clark gets his "Christmas bonus" he starts going off about what a lousy guy his boss is. During his outburst you can see a crew member's head pass by the bottom left corner of the screen. (01:15:55)
Continuity mistake: After the tree burns up from Uncle Lewis' stogie, he turns around revealing fire on his back. Right as he is turning, the shot cuts to Clark and back to Lewis. In this new shot, Lewis' hair is different (compare the wigs), indicating the person getting the fire on his back put out is a stunt person.
Revealing mistake: When the Santa Sleigh is launched in the air by the ignited sewage, the sleigh flies over the moon. Now on the DVD version of the film, it's not clearly visible, but on the VHS version, you can clearly see there's a box around the sleigh that looks like the sleigh is under a microscope slide. (01:32:50)
Other mistake: Another note about Clark's falling through the ceiling and onto his son's bed: Take note of the shot of him in the attic after falling through the ceiling. He's standing on the upper bunk of the bed now, but from the shot in the attic, he's only down to his knees or so. Assuming his home's ceiling joists are 8 inches or so, then the mattress of the upper bunk would have to be no more than, say, 10 inches from the ceiling for that much of him to still be in the attic while standing on the bed. I've never seen a bunk bed whose upper bed gave you less than a foot of space between mattress and ceiling! (00:33:05)
Suggested correction: The bunk bed is not normally used by two people - there is a scene in the kitchen where Audrey talks about having to share with her brother. It is possible that this bunk bed used to be in a different location, but has been shifted to this lower ceiling at some point in the past.
Continuity mistake: In the opening scene, when the family is on their way to get a Christmas tree, they get into a road rage battle. If you look closely at the shape of the headlights, the car the family is in and the stunt car are noticeably different.
Continuity mistake: When Clark has the entire family outside to witness the lighting of the house, the positions of the in-laws change instantly from being clumped together to strung out in a line, depending on whether the shot is overhead or at ground level.
Character mistake: Clark has too many lights on his house causing the city to go dark. There is a scene where the power plant needs to boost their output. There is a close-up of a guy flipping the switch. Look at the way they spelled auxiliary - auxilliary. (00:37:54)
Revealing mistake: When Uncle Louis drops the match in front of where Eddie empties the "chemical toilet" if you look VERY close you can see the rope that launches him into the air. (01:32:05)
Continuity mistake: When Aunt Bethany asks "Do you hear it?", she leans forward in her chair. In the next shot she's suddenly sitting back, and leans forward again when she says, "It's a funny squeaky sound."
Continuity mistake: When Clark is outside, trying to get the lights to work, Ellen comes out the door, pulling a sweater around her shoulders. First it is on one shoulder, then both, then one, and at the end of the scene she has it on properly, with both arms in the sleeves. (00:36:10)
Continuity mistake: When Uncle Lewis lights the cigar that sets the Christmas tree on fire, watch closely. It shows side shots of Clark eating his dinner, and you can see the tree in the living room. The camera cuts back to Lewis lighting his cigar, and then back to Clark at the exact same angle as before. The tree is gone. (01:11:10)
Revealing mistake: After Eddie kidnaps Clark's boss, he drives off and if you look at the ground the snow looks like soap bubbles, because you see them waving around. (01:23:36)
Visible crew/equipment: When Clark is on his sled, just before he crashes into the cabin, the shadow of the camera is visible on it. (00:50:50)
