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.
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.
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)
Continuity mistake: When Clark is going crazy, he cuts the newel post. But it's still in place in the later scene, when the family has problems with the squirrel. (01:18:15 - 01:21:20)
Continuity mistake: After Clark receives what he thinks is his bonus check, he says if there is enough money left over he will fly all of the relatives out to see the new pool. Everyone reacts with excitement, particularly Ellen, who is standing right next to Clark. She lets out a cry of excitement and raises her arms. The next shot is taken from the opposite point of view (from over Clark's shoulder). In this next shot, you can see everyone else still excited with the sudden exception of Ellen. She went from shrieking in excitement to having her mouth closed and her arms back down at her sides.
Continuity mistake: When Clark is going into the attic to hide presents, the ladder that smacks him in the face is a sliding ladder, but later when he is shut in the attic and uses the ladder to attract attention it is a folding ladder.
Continuity mistake: When Clark's uncle drops the match that sets the sewer on fire, his toupee falls off and at the end of the scene you can see him trying to put it back on, although it's burnt pretty badly. In the final scene where everyone is dancing around, his toupee is back on and in perfect condition. (01:32:35)
Continuity mistake: When Clark finally opens the christmas lights, he has the wires in his hands. The shot later, when all the family comes, the wires are not there and his arms are wide open. (00:39:55)
Continuity mistake: When Clark is holding the gutter, it bends and ice is thrown from inside of it. The problem is that you can't see any ice during the first shot when it bends, and also that the ice goes in the wrong direction. (00:24:25)
Continuity mistake: At the end of the movie, when Clark is outside of the house with Eddie's dog, all the police cars have disappeared. (01:34:10 - 01:35:00)
Suggested correction: It's the end of the movie with credits rolling, I would think the people behind the movie wanted it that way with Clark looking proudly of his Christmas night. his last line in the movie, he said "I did it" and the lights went off on the "THE END" sign. So, that's what I think about the ending. It's not a mistake. It would be if the sign wasn't shut off and started rolling credits after he said his line and nothing's there.
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.
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.
Continuity mistake: When Clarke is installing the Christmas lights, the rope on the ladder keeps appearing and disappearing. (00:23:00)
Continuity mistake: When the squirrel is being chased by Eddie's dog, it passes through the broken door and then vanishes. (01:22:07)
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.
Continuity mistake: When they first step up to the tree in the forest, Audrey is still moving. In the overhead shot, she stops, and we can see tracks in the snow where all four have been standing. The problem is, there are a lot of tracks. We're lead to believe they just walked up to the tree.