Continuity mistake: When Marley comes into the drug store to see Kevin, the wrapping paper is leaning on the shelves, but in the next shot the wrapping paper is gone.
Continuity mistake: When Kevin puts the spider on Marv's nose you can see a box of junk is almost halfway off the steps of the attic but in the next shot at the start of the film the box is no longer halfway off the steps.
Continuity mistake: When Kevin is washing dishes, there's Bubbles on his hands, but in the next shot there's no bubbles on his hands.
Continuity mistake: Harry and Marv both get hit with the paint containers on the stairs. Look at the front doorway when Marv gets hit. The cord (from the hot implement attached on the doorknob) is in an 'S' shape and lots of micro machines litter the doorway. Harry then gets hit. When he gets up to go up the stairs after Kevin, the cord has moved and the micro machines are well clear of the doorway.
Continuity mistake: When the 2 burglars are breaking into the McAllister home, the tall burglar gets hit square in the face by an iron...he has iron marks on his forehead and cheeks but not his nose...how could the iron not hit his nose?
Continuity mistake: In the supermarket when Kevin puts the groceries on the conveyor belt, he sets the tissue paper standing up. The next shot of Kevin shows the tissue on its side and farther back, the next shot it's back to its original position.
Continuity mistake: Right before Kevin destroys the shelves after climbing up to reach the metal box, the box with Buzz's life savings (on top of the shelves in his room) moves between the overhead and ground shots.
Continuity mistake: Buzz is eating pizza in front of Kevin and shoving it into his mouth. The scene changes and the pizza in his hand is larger now. Another change and it's small again.
Continuity mistake: When Buzz is eating the pieces of pizza in front of Kevin, the frontal shots of Buzz show him eating with his left hand, but the shots over Buzz's right shoulder (facing Kevin) show Buzz eating with his right hand.
Continuity mistake: Kevin's hands change during the micro-machines sequence. He is sitting at the top of the steps, and puts his right hand down. In the next closer shot, both hands are in a different position.
Continuity mistake: After Kevin's whole family comes home, he walks straight to the window to look out. If he had done that, he would be looking out of the side of the house, but he is obviously looking out the front of the house to straight across the street.
Continuity mistake: When the delivery guy stands outside the door and Kevin plays the movie, in the shot from Kevin you see the red curtains are more wide open and you see the silhouette from the delivery guy. In the shot from the delivery guy the red curtains are suddenly more closed and his silhouette couldn't be showing through.
Continuity mistake: When Kevin puts the groceries on the belt, there's 2 packs of toilet paper. One in the front and one in the back behind the orange juice. When she scans the orange juice, the other pack of toilet paper isn't there.
Continuity mistake: When Kevin climbs on the shelves in his brother's bedroom you can see the spider switch to left and right.
Chosen answer: They did but the power and phone lines were down due to a tree branch that had fallen on them the night before the family left. A flight attendant on their plane mentions that attempts had been made to call the McAllisters' home but "the phones are still out of order".
Jeff Swanson
But how did he call the police at the end if the phone lines were down.
That was several days later. Clearly the phone lines were repaired over the course of the film.
The film takes place over 3 or 4 days.
Ssiscool ★
After the storm the lineman tells them the power has been restored but the phone lines are "a mess" and that it would take several days to get them fixed. They were out initially, and then in various stages of repair afterward.
Also explains calling for a pizza.
Ssiscool ★
It's ridiculous though that the phones are apparently working by the time they land (Kate's SIL calls everyone on their street). Yet none of them try the house again.