Continuity mistake: At the beginning of the movie, the Griswold family makes marks in the snow when they arrive at the tree which Clark wants. A shot later, the marks are bigger even though they haven't moved. (00:08:05)
Continuity mistake: When Clark is outside hanging the lights, he staples the sleeve of his shirt, under his wrist, to the eaves of the house. In the next shot, as he is pulling, the shirt is stapled over his wrist. (00:21:50)
Suggested correction: The position looks the same if you consider hand movement. Look at the opening of the sleeve and the hand position for comparison. I don't think this is an error.
Visible crew/equipment: When Ellen opens the door after Clark falls from the tree, there's a strange white thing visible for a few frames at the upper left of the door. Might be the hand of a crew member opening the door.
Revealing mistake: When Clark and Eddie push the chair to see what happened, the burned cat is only visible in closeups. There's also a blue object next to the couch that look like an iron that is creating the smoke effect.
Continuity mistake: When Clark's neighbours return home, the man says to Clark, "Where do you think you're going to put a tree that big?" The trunk is very large, bigger then Clark's feet. Clark replies, "Bend over and I'll show you." Then Clark cuts the tree trunk - it is very thin and easy for him to cut.
Audio problem: During dinner on Christmas Eve there is a shot of the cat chewing on Christmas lights. The sound of the cat chewing is a fraction of a second off.
Continuity mistake: When Clark is stapling the lights to the roof, his leg is tangled in the sting of lights causing him to lose his balance and slide of the roof. As he slides/falls grabbing the gutter the string of lights around his leg disappears.
Factual error: The family is reacting to where Clark went flying down on his saucer, ending up in a Wal-Mart. With the speed and length of the trip, he would've been out of sight in seconds. There was no way that they could see him from where they were.
Continuity mistake: After Eddie's arrival Clark is on the lawn with "Snots." Clark's left had is shown as he is there alone with the dog trying to get his attention and his glove and wedding ring have both disappeared.
Visible crew/equipment: Just as Clark is about to smash through the hut on the greased up sled, the shadow of the camera is on the hut. (00:50:57)
Continuity mistake: When the grandfather is sleeping in the top of the bunk bed, there's a cheesecake poster on the ceiling. When Clark falls through the attic floor onto the bunk bed, it's not there.
Continuity mistake: The first time Clark fails with the lights, Ellen's mother says she hopes the kids see what a waste of resources it is. During this scene the level of her martini changes.
Continuity mistake: When Santa Clause's sled passes in front of the moon at the end, why is the sea so dark? It wasn't in previous shots.
Plot hole: When cousin Eddie kidnaps Mr. Shirley, Shirley's wife immediately calls the police. She describes Eddie as 'brutish and huge' or something similar, and wearing a 'blue leisure suit'. She also mentions that she got the license plate number of the vehicle. But how did the SWAT Team know to go to the Griswold's house to find Mr. Shirley? Eddie's RV is not registered in the Griswold's name so the plate numbers would not be much help in finding the culprit.
Continuity mistake: During Clark's rant, the shot goes from seeing him from behind the whole family to a frontal view of the family looking at him in shock. In the first, they are standing in line with the entrance to the room. You can even see Eddie's shadow on the wall as he's very close and slightly behind it. Also, on the other side, Audrey's arms are going down to her side and she's a little behind Art. In the next shot, there is no wall and Audrey is in front of Art. Her arms are also crossed.
Factual error: Even though this movie takes place at Christmas and there is lots of snow around the outside of the house, you can tell this was filmed during the summertime due to the short shadows in some outside scenes. At Christmas time, shadows are longer all day long.
Other mistake: When the lights don't work, Clark punches Santa and knocks the antlers off the reindeer. When the lights come on and the family comes out, the antlers are back on their heads.
Continuity mistake: When Clark is looking at his "bonus check", he's holding both the envelope and "check" together in both hands. In the next shot he's only holding the "check" in both hands and the envelope is no longer under it.
Continuity mistake: When Clark falls over while on the ladder, after ripping his sleeve off, his hands keep changing position on the ladder. When he first starts to fall, his right hand is gripping the side and in the next shot both hands are gripping the rung. In the next shot both hands are on the side of the ladder until the shot after he pushes himself away from the tree and they go back to being on the rung for a shot.
Factual error: When Clark is sliding on the saucer, he shoots out a shower of sparks when he crosses the street. Those old saucers were made of aluminum, and aluminum can't create sparks like other metal does.
