Continuity: Harry protects his burnt hand with a handkerchief when he climbs along the rope towards the tree house, but alternating shots show the tail of the handkerchief either sticking out or not.
Factual errors: The underside of a Nissan Quest, actually a front-wheel-drive car, appears to have rear-wheel drive.
Continuity: When Kevin's father calls the Murphy home while Harry and Marv are robbing it, Marv picks the entire phone off the table. At this point a receiver is visible on the phone. In the next shot of Marv, it is gone. If it was in fact supposed to fall off, the answering machine would have been cut off anyway.
Revealing mistakes: As Kevin flies through the air outside the front door after he sleds down the stairs, you can see the rollers on the bottom of the toboggan.
Revealing mistakes: Obvious stunt double in the long shots of Kevin swinging across to the tree-house.
Continuity: When Harry grabs the heated doorknob with the "M" engraved on it, he grabs it with his knuckles at 9:00, facing left. After he puts his hand in the snow to cool it, he looks at it and sees the "M" upright on his hand.
Revealing mistakes: When the McCallisters are leaving in the morning and the neighbor boy is talking to the van driver, he is mouthing the driver's lines (the first time the driver speaks).
Continuity: The blind spot mirrors on the burglars' van change positions and sometimes disappear between shots.
Continuity: Harry is seen wearing a wedding ring in the shot where Marv tries to kill the spider that is on Harry's chest. Later in the movie Harry is no longer wearing the wedding ring.
Revealing mistakes: When Kevin is sliding down the steps the toboggan is lined-up with the stairway, when he goes out the door, the toboggan is now lined-up with the doorway. He should have just crashed into the wall and not gone out the door.
Continuity: The stained glass window in the church is different in the interior and exterior shots. Seen from outside, it has four panels, while inside it has seven.
Revealing mistakes: When the whole family arrives in Paris (which is really the underground walkway under the O'Hare Airport Hilton, that connects the terminals at O'Hare, and looks like it may include parts of the old Terminal 4), Kate uses a public phone to call home. But this device can't be a French one, because all phones available in France in the 90s required telephone cards and we clearly hear an operator asking Kate to insert coins.
Continuity: When Kevin first uses the BB gun to shoot the figurines down the laundry chute, he pumps the rifle forward and then back at 23:21 on the DVD. Later in the film when he prepares to shoot the two robbers through the dog door, he pumps the rifle back and then forward at 76:12.
Continuity: The plane that takes off from Chicago is a DC-10, but the plane that touches down in Paris is a Boeing 757. Likewise, the plane that lifts off from Paris is an MD-80 (of which the range is inadequate for a flight from CDG to any US airport), while the one that lands back in the United States is a DC-10.
Revealing mistakes: After Marv is hit with an iron, a wrinkle can be seen in the mark on his face revealing that the iron print is actually a plastic sticker. It can also be seen later when Kevin puts the tarantula on Marv's nose.
Continuity: After Harry touches the heated doorknob and Kevin flees from the door at 80:48-80:51 on the DVD, the charcoal lighter cord runs out of the foyer into the next room from which the camera is shooting. Later, when Harry and Marv are hit with paint cans at 84:18, the door and the red-hot charcoal lighter can be seen in the background, but its cord does not leave the foyer.
Errors made by characters (possibly deliberate errors by the filmmakers): When Kevin is shooting at the toys that go down the laundry chute, he is closing the wrong eye for aiming a rifle.
Continuity: When Kevin walks up to the church at night, there is a door clearly in the very center of the building. When Kevin is shown inside the church, there is a baptistery in the center where the door was on the outside.
Factual errors: American Airlines has never flown a morning flight between Chicago and Paris.
Factual errors: When Kevin calls 9-1-1 to report that robbers are in his house, he uses a phone that says "Pacific Bell", which isn't available in Chicago.
Continuity: When Heather is told to count the kids before they load the vans, she counts herself twice which would mean they are missing two kids for the trip. She counts herself as number three and then the neighbor boy in place of Kevin, but then counts herself again as number eleven. Both times she touches herself on the head to prove the miscount.
Continuity: When Kevin is at the top of the stairs getting his sled ready one shot shows him throw his scarf over his right shoulder and it slips down his arm. In the next shot, from behind, the scarf is clearly thrown behind his shoulder.
Continuity: When Harry slips down the stairs while trying to go in through the front door, he drops his crowbar and doesn't pick it up, but in the next long shot the crowbar is no longer on the ground right next to the steps.
Revealing mistakes: When Marv is hit in the face with the iron, if you look closely before he falls down you can see that the iron hits him on the forehead, but when he sits up, the iron has left a print that covers his whole face.
Incorrectly regarded as goofs: When the pizzas arrive, the guy says the cost will be $122.50. In the kitchen, however, Peter says "Ten pizzas times twelve bucks.", which would mean the pizzas should cost $120.00. For the pizzas to cost $122.50, they would need to cost $12.25 each. However, the extra $2.50 was most likely added as a delivery charge, or an automatic gratuity considering the size of the order.
Incorrectly regarded as goofs: When Kevin first speaks to the fake Santa about giving a message to the real Santa, he says that his address is 671 Lincoln Blvd. Later on, when the thieves are running through his house, he calls 9-1-1 and tells the operator his address is 656 Lincoln Blvd. This is done so that the police will arrive at the Murphy's house, where Kevin is planning to lead the burglars (as evidenced by Kevin's statement: "My house is being robbed. My name's Murphy.")
Continuity: When Marv goes to look and see if anyone is home, Kevin is washing up and has his sleeves rolled up. He plays "Angels with filthy souls" and gets fire crackers out. He reaches into a drawer to get a lighter and we only see his arms where his sleeves are down. When you see a full view of him, his sleeves are rolled up again
Incorrectly regarded as goofs: When Kevin makes the sign of the cross before eating his dinner, he makes it what would appear as wrong, touching his right shoulder first - however, some eastern catholics, such as Byzantines, bless themselves this way.
Revealing mistakes: In the film that Kevin is watching, "Angels With Filthy Souls", Johnny shoots Snakes with a Thompson machine gun. Snakes is standing in front of a door with a glass window. At the short range that Johnny shoots him, at least some of the bullets would have gone right through Snakes and broken the window.
Continuity: When Kevin is watching TV in the kitchen, there is a gingerbread house next to the TV in shots directly facing the TV. But when the shots are from the side (on Kevin watching TV), the gingerbread house is not there.
Continuity: The house loses power in the night from the falling tree branch. This causes them to oversleep. The power gets restored before they leave, obviously, because we see the parents' alarm clock showing 12:00. Later, after the family has left, the burglars arrive and Joe Pesci's character shows-off by telling what time each house's timer is set to turn the lights on. The timers would be on the wrong time when the power was restored.
Incorrectly regarded as goofs: As Harry is driving down the driveway after a burglary he is wearing his black knit cap. Just after he hits the brakes to avoid hitting Kevin he pokes his head out to tell Kevin to be more careful and his cap is missing. However, he can clearly be seen removing his hat as he is winding the window down to talk to Kevin, which is why he is not wearing it in subsequent shots.
Continuity: In the scene where Harry and Marv try to follow Kevin out of the window to the tree house, the rooftop is shown and there's no snow on it. Although the ground is covered in (obviously fake) snow.
Errors made by characters (possibly deliberate errors by the filmmakers): When Kevin is at the counter of the grocery store, the clerk scans a bag of toy soldiers and looks at Kevin. He says "It's for the kids". But when the clerk asks, "What about your brothers and sisters?" Kevin replies, "I'm an only child".
Errors made by characters (possibly deliberate errors by the filmmakers): In the beginning of the movie after Peter realizes he will not be able to shave in Paris without a power adapter, Kate tells him to grow a goatee. This would be impossible, since a goatee would still require shaving part of your beard.
Crew or equipment visible: Near the end of the film, as Kevin looks out of the window to see his neighbor reunited with his son, a hand holding a camera is clearly visible.
Continuity: When Kevin goes across the street to his neighbors house, entering though the flooded basement, his clothes are soaked he rushes up the stairs. In the next scene where he goes though the door to run into Harry and Marv, his clothes are dry.