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: 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.
Revealing mistake: When Clark notices that Lewis has caught on fire, he's only burning when he pushes him on the ground.
Continuity mistake: As Clark is stapling the Christmas lights to the house, there are bits of snow and ice on his left-hand glove in the close-ups. But in the longer shots of Clark, the glove has no snow and ice present.
Continuity mistake: In the department store as Clark is talking with Mary, the lingerie sales lady, his left arm is supporting him on the glass counter as he is standing. The next shot when Rusty approaches, Clark is now bent down with his left arm resting on the counter.
Continuity mistake: After Clark cuts the rope restraining the tree branches, Rusty is very close to the tree, but the final shot when Clark gives the "OK" sign shows Rusty about two feet from the branches.
Revealing mistake: When Snots the dog chases the squirrel into the Griswolds' dining room, he barely brushes a high-back dining chair that immediately falls on its side. If you look closely, a string attached to the the right side top of the chair can be seen tightening which then pulls the chair down.
Continuity mistake: In the scene of Clark standing in the snow trying to figure out why his Christmas lights did not work, the paper he is holding in his right hand is mid torso to him, but in the next shot when Rusty leaves him, his right hand has instantly dropped to his side and he raises his paper-holding hand again.
Continuity mistake: When Clark, Eddie, and Catherine are admiring the Christmas lights of the Griswold house, Clark is very close to Eddie with his left arm draped over Eddie's shoulder, but the next quick cut to Clark when he says, "Eddie?", shows Clark further away and his left arm at his side, and not stretched out.
Revealing mistake: The stunt double for Nicholas Guest is obvious after Julia-Louis Dreyfus punches him. The hair style of the stunt double is different from Nicholas Guest's hair, which is heavily slicked back.
Continuity mistake: In the Christmas dinner scene, closeups of Rocky show his right hand raised to his face, but the overhead shots do not.
Continuity mistake: When Todd, the snob neighbor, falls down the stairs, his wife Margot is not visible in the bedroom. (00:38:55)
Continuity mistake: After Clarke falls in the bush, the gutter repairs itself.
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)
Continuity mistake: When the family is on the front lawn to inaugurate the Christmas lights, between shots a blue Lincoln at the curb disappears and a station wagon appears across the street.
Visible crew/equipment: When Eddie and Clark are putting the burned chair in the garbage, you can see the shadow of the camera following them.
Continuity mistake: When Rocky runs out of the RV and stands in front of his mom, her mittened right hand is on his shoulder but in the next shot it's not.
Continuity mistake: When Eddie and Clark are drinking eggnog, Eddie knocks down the decoration with propellers on it. When Eddie walks to the table with the nuts on it the camera shots cut from Eddie to Clark attempting to fix the decoration. In each shot that we go back to Clark, the number of propellers left on the decoration change even after Clark has given up fixing it. (00:45:55)
Revealing mistake: When Julia Louis-Dreyfus has the dog jump on her, you can tell it's a stunt double. In the shot of Julia, the gem on the back of her sequence dress and her hair doesn't go below the gem. When Snot is about to jump on her, the hair completely covers the gem and is much fuller and looks like a wig.
Other mistake: When Clarke and Eddy are drinking eggnog by the tree, and Snots is drinking the tree water, look at the tree's trunk. It's a birch tree not a pine.
Suggested correction: You actually see Clark go from sitting on the counter to bending down as the saleslady is modelling the undergarment.
That's not the part the mistake is talking about. The mistake is valid. Clark is sitting in the counter but is off screen when he changes position (so you don't actually see it). When Rusty enters the shot, Clark's hand ion the counter. In the next shot, his elbow is on the counter, with no time elapsing.
Bishop73