Continuity mistake: When Mrs. McCallister receives the phone call about the police finding Kevin, as soon as she answers the phone, notice the white shirt behind her on the bed. When she tells the family they found him, the camera goes back to her and the shirt is in a totally different position.
Continuity mistake: At the pageant scene, when Kevin turns to attack Buzz, you see him make a fist; but when the camera shot changes to include the full choir and the audience, you see Kevin push Buzz with a open palm.
Continuity mistake: In the final scene, Kevin approaches the pigeon woman. She says "Merry Christmas" without any pigeons on her head. The long shot is taken, and she now has at least four pigeons are sitting on her head. A close-up is taken when Kevin approaches and reaches her hand, and again, pigeons have disappeared from her head. Impossible to have the pigeons flying on and off her head in the space of half a second.
Continuity mistake: When the robbers are in Duncan's Toy Chest at midnight, Kevin sets up his board on the bucket outside the window. He then knocks on the window, takes the robber's picture, then runs back away and pulls a rock out of his pocket to throw through it. But he wouldn't have been able to run back that far without jumping over the bucket and board, and he did not jump or avoid any obstacles.
Continuity mistake: Once Kevin and the attendant board the plane to NYC to make sure Kevin's family is on board, there is a shot of Kevin while he says, "There's my dad over there." In the background, a man is sliding his black coat off of his shoulders. Two shots later when the attendant says, "Well, go find an empty seat," in the background you will see the exact same man taking his coat off a second time.
Continuity mistake: After Kevin throws a few bricks off the roof, a brick is lying at Marv's feet. In the next shot, it is gone. When Harry disappears, we see three bricks, all on the road and none by Marv.
Continuity mistake: When Kevin bumps into the lady at the airport you see the guy who Kevin thinks is his dad run through the door and out of sight. In the next shot, you see him walking through the door.
Other mistake: When Marv ends up stepping on some green gunk that Kevin set as a trap in the basement, he eventually slips and then slides into a shelf of paint. However, Marv actually started sliding after he fell to the ground. It's almost as though he was being pulled forward. How could he have slid?
Continuity mistake: When Kevin is buying some toys at Mr. Duncan's Toy Store, he pays for the toys and there is a can full of pencils to the right of Kevin. As the camera switches shots to Mr. Duncan and back to Kevin, the pencils are in different positions every time.
Continuity mistake: When Kevin is throwing bricks from the top of the apartment building, note the position of the gym bag beside Marv - it is in the wrong place, positioned differently, during one of the cutaway shots between Marv and Kevin.
Revealing mistake: In the scene when the bandits are in the uncle's house at the bottom of the stairs, the tool chest falls down. When it hits the door and they slide back if you look closely you can see that they are on rollerblades.
Revealing mistake: When Kevin arrives at the airport in New York (filmed at Chicago O'Hare) and goes up to the agent to ask her what city is outside the window, one of the destinations on the board at the gate is New York - LaGuardia...giving away that the scene was not shot at a NYC area airport.
Plot hole: The sheer distances Kevin covers on foot in one night are outrageous. Between 9pm and midnight he walks from Carnegie Hall to the children's hospital, to 95th street, back to the toy store carrying a large paint can and a large 2x4 (street signs here put it around 59th and 5th), back up to 95th, then all the way back to midtown, to Rockefeller Plaza. One way from W 95th street to around E 59th and 5th Ave. is at least an hour on foot for an adult, he does this 4 times between 9pm and midnight, once while carrying a 2x4 and paint can, once while being chased by 2 adults, and he still has time to set up a house full of traps.
Other mistake: When Kevin is checking in, the time on the clock behind the front desk lady doesn't change from 2:52 over the whole course of time that he's checking in.
Revealing mistake: Makeup is visible before the first brick hits Marv Merchants.
Visible crew/equipment: As Tim Curry exits the lift to secretly search Kevin's room, at the bottom right hand corner a shadow that looks like a hand appears on the wall to the left of the lift, inconsistent with the movements of him exiting the lift. You have to be quick, as it appears on widescreen as the shot moves away from the lift doors.
Continuity mistake: When Harry and Marv catch Kevin for the first time, coming out of the hotel, they walk away and are standing at the traffic lights. The camera angle is Kevin looking up at Harry and is from below Harry's elbow but Kevin's height makes this impossible seeing as he is up to Harry's shoulder.
Other mistake: In the scene where Kevin is being chased through the Plaza lobby, the large brass/marble table, usually in the center of the room, has been moved to one side to allow the characters to freely run through the area. The table has been purposely moved as it is right next to the concierge desk which would pose an inconvenience to any guests and so, therefore, is not a natural occurrence. After all three fall over, it is evident that a large space has been cleared, as it allows for Cedric to be dragged away as well.
Continuity mistake: After Kevin pushes Buzz, causing all the singers to fall over, Kate and Peter who are sitting next to each other, both stand up. But in the next close-up shot, Kate is standing alone.
Revealing mistake: When Kevin breaks the pearl necklace while being chased by Harry and Marv, the hands doing the breaking are not Kevin's, they are much too big to be his.
Answer: He's heading back to the hotel most likely to apologize for spending such a huge amount.