At one point when Snots the Dog is chasing the squirrel through the house, they run over the top of the dining table, and the food, plates, and silverware get demolished. A moment later, Clark is walking past the hallway leading to the kitchen with the table visible in the background. The tablecloth and setting are in pristine condition.
The square block on the railing at the top of the stairs that Clark cuts off with a chainsaw reappears when the guests run upstairs to escape the squirrel.
The police cars speeding to the house were all Ford. Later, when scenes are shown with police cars parked in the background, they are all Chrysler.
From the interior of the house, the attic ladder is shown as a slide-down, but from the attic, it has a fold-out design.
When Clark is polishing his sled, the bottom is smooth, but when it is going through the forest there are fins on the bottom.
Twenty-five thousand 7 watt C9 bulbs would draw approximately 1,458 amps. A typical residential home has a 150 to 200 amp box. Either the main breaker would trip or the single light switch in the garage would melt instantly. (This may not be a goof but an intentional comic absurdity).
Clark Griswold's Ford Taurus station wagon is shown to have exterior wood paneling, an option that was never available on this car. (However, it's possible the exterior appliques were added by the filmmakers as a nod to the "Wagon Queen Family Truckster" the Griswold family bought in Vacation (1983).)
Clark informs Eddie that the sewer is a storm run-off sewer, implying that the waste material Eddie is pumping into it will not be treated; additionally, with the absence of precipitation or significant melting, Eddie's chemicals remain stagnant until the end of the film. In reality, Chicago has a single, unified sewer system; storm run-off and wastewater run through the same mains for processing by the MWRDGC and the mains are therefore constantly flowing with effluent.
When Clark is walking around in the attic he continually walks beneath the slats which would have immediately resulted in him going through the sheet rock and punching a hole in the ceiling.
When the Macy's Thanksgiving Parade is shown on the television, the channel is set to 06, which isn't available in the Chicago area. Chicago has odd numbered channels; Milwaukee has the even numbers, which includes channel 6 which is WITI, now 6.1 on digital over-the-air broadcast.
The family Christmas tree shrinks smaller and smaller throughout the movie. This could be because they trimmed it back considerably so it didn't take up the whole room.
When Clark says he wants his boss "brought here" to confront him about his Christmas bonus, Eddie leaves to go and get him. Eddie is visiting from Kansas. How did he know where to go to find Clark's boss? Clark mentioned "Melody Lane" but didn't give the exact address. Eddie could easily have looked up his address in the phone book, or in company documents Clark surely has in his home.
When Clark is locked in the attic, he sees a movie reel marked "Christmas 1959," but when he's later watching movies, it says "Christmas 1955." However, there might have been several year's worth of Xmas movies, and the first one we see him watching wasn't necessarily the first reel he looked at in the box.
Furthermore, the first home movie is in color, likely the 1959 movie whereas the 1955 one is in black and white.
Furthermore, the first home movie is in color, likely the 1959 movie whereas the 1955 one is in black and white.
In one scene after all the parents have come to the Griswold home for the Christmas holidays, they are all seen sitting watching the Macy's thanksgiving day parade. This parade occurs in late November not the middle of December. This could have been an encore presentation or a VHS recording of the parade.
The swimming pool brochure Clark shows his coworker is for an above ground pool. The amount of money he states he has invested and his daydream both refer to the pool as an in-ground pool. It's likely the company installs both in-ground and above-ground pools. It doesn't mean the company doesn't do in-ground pool work too.
A tow rope is visible pulling Clark's sled.
Right before Clark goes to try out the lubricant that is "500 times more slippery than cooking oil," the pyrotechnic line that Clark takes can be seen going down the hill before it ignites.
When Eddie leaves Frank's mansion, the "snow" in the driveway wiggles.
When Clark gets trapped in the attic, skylights are visible, yet from the outside of the house, they are gone.
After Clark's encounter with Mary, the underwear salesgirl, a shot of the street and house is shown, and a tree can be seen in the front yard, with the fake-snow covered leaves blowing in the wind.
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 touches the cabbage.
Clark uses a mechanical stapler to put up the lights on the house. The sound of the stapler is that of a power stapler that is powered by an air compressor.
When Clark is sledding down the hill, he passes a school bus. The school bus has the sound of a Doppler truck horn, rather than a school bus horn.
About midway through Clark's rant, a crewperson's head dips into the bottom left corner of one of the long shots.
Several shots show the dining room has no ceiling, but rather a grid of beams.
After Clark cuts the Christmas tree and the tree expands to its natural size, the second tree limb to break through the window has a 2x4 attached to it. This must have been used to push the branch through the glass.
Just before Clark takes off down the hill in the sledding scene, there is a shot looking down the hill where you can clearly see the wires/cord in the snow that are used to make it look like the snow flies in the air as the sled races down the hill.
When Clark is getting his coffee in the office talking to his co-worker, the crew is reflected in the coffee pot.
The Christmas tree trip shows small mountains in the background and log-hauling trucks on the highway, neither of which accurately represent an Illinois landscape.
Due to being partially being filmed in Burbank (Griswold's residence) one can occasionally spot California vegetation in the background, such as ivy climbing telephone wire and southern California coniferous trees.
When Ellen and Clark are outside alone trying to light the Santa, a "wet-barrel" fire hydrant that cannot possibly be used in Chicago, IL due to freezing is visible. This type of fire hydrant is found in Southern California where there is no chance of freezing.
Cousin Eddie, upon describing his true plight to Clark, proclaims that the "Gas money give out in Gurnee." It is strongly implied that Eddie and the family traveled from the state of Kansas as it is clearly stated during the kidnapping scene that his RV has license plates from there. The city of Gurnee is 40 miles north of central Chicago. There is not a single viable route from Kansas to Chicago that goes through the city of Gurnee.
When Clark cuts down his own pine tree in the front yard, the way the tree fell through the neighbor's window implied the tree was in the rear yard.
At the beginning, the Griswolds are driving home with their new Christmas tree, roots and all, yet they brought no tools with them. All four of the Griswold's together could not uproot a 25-foot tall tree, let alone strap it to the roof of their vehicle without tools or equipment.
When the Christmas lights go on by accident the first time, their extreme brightness is enough to cause the obnoxious neighbors to shut their eyes even though they are indoors and not looking directly at them. Yet Ellen is in front of the house and looking right at them yet experiences no blinding effect.
No mention was ever made of that big hole Clark put in the ceiling above the top bunk that made a big mess. Since one of the grandparents was sleeping on that bed someone should have said something.
When Clark hands Rusty the knot of lights, you can clearly see that many sockets are empty. Clark may have plenty of bulbs for the sockets but it is never mentioned.
When Clark starts his downhill sled run you get a good look at the surroundings before he starts and it's clearly difficult to see beyond the trees (particularly at night). When Clark does his downhill sled he goes beyond the woodlands, goes a long way down hill, crashes through 2 high mounds of snow (which stay intact), goes further downhill, crashes through a shed (which again doesn't collapse), goes further downhill, causes multiple vehicles to skid and swerve all over the place (one of which is a large bus) before ploughing through a mound of snow and then coming to rest in a Walmart car park. At the end of all this, his family (whom are back where he started) grimace as though they can see him crash which would be impossible given the distance that he travelled, all the objects in the way and the night time conditions.
When Clark first turns on the Christmas lights, the shot from the power company has the word "Auxiliary" spelled incorrectly.
Clark says he has 25,000 lights on his house. These are the old-fashioned bulbs that draw 7 watts each; thus, Clark would be drawing 175,000 watts of power, or 175 kilowatt (kW) continuous draw, far more than can be delivered to a single-family dwelling using the U.S. standard 120/240-volt electrical system. Therefore, Clark's main breaker would have instantly tripped the second he would have plugged in all the lights at once, not counting the lights on his Christmas tree and everything else electrical in his house.
Clark Sr. says "if one goes out the whole thing doesn't work" about the Christmas lights on the roof. While this is the case for lights on a serial circuit, the lights Clark puts on the roof are on a parallel circuit. If one bulb went out on these lights it would not affect the rest of them.
When the attic ladder slides down it hits Clark in the mouth and jaw. When he's climbing into the attic in the next shot he's rubbing his forehead.
In this film, Rusty is much shorter than Clark, has short, dark hair, and has a higher-pitched voice. But in the film "European Vacation," which takes place before Christmas Vacation, Rusty is as tall as Clark, has long blonde hair and a deeper voice.
This is a running gag in all the National Lampoon's Vacation films. Clark and Ellen are the same actors, but Rusty and Audrey are different actors that look nothing like the ones in the other movies.
This is a running gag in all the National Lampoon's Vacation films. Clark and Ellen are the same actors, but Rusty and Audrey are different actors that look nothing like the ones in the other movies.