Continuity mistake: When Kevin is preening himself in the mirror while giving a running commentary of his washing habits, you can see the shower gel (facing forward), aftershave and deodorant to his left by the sink. When it cuts to a close shot, a bottle of fragrance has mysteriously appeared by these items and the shower gel is facing away from Kevin.
Continuity mistake: When the McCallisters leave Chicago, they are flying on a DC-10. The plane that arrives in Paris at the end of the flight is a 757. If they changed planes en route, don't you think that the McAllisters would have noticed that Kevin was missing? He isn't old enough to hold his own passport and his parents would have to be there when he boarded the second flight.
Continuity mistake: In the scene where the robber is breaking into the basement, the steps and concrete by the door are icy. However, when the camera angle changes and it shows the same scene looking out of the basement, there is no ice at all.
Continuity mistake: When Harry is telling Marv when the Christmas lights on the house are going off, right before they are going to rob the house, they show the dashboard of the van. There is nothing on it. When they pull into the driveway, there's paper and other things on the dashboard.
Continuity mistake: As Kevin runs away from the nativity scene after hiding from the Harry and Marv, his scarf is done up to the right (over his right shoulder). When he reveals himself from the nativity scene from under the green robe, his scarf is done up to the left (over his left shoulder).
Revealing mistake: When Harry walks around the side of the house towards the front door, in the shot which shows Harry walking from side-on, this is obviously a stand-in, given this person is much taller than Joe Pesci (who plays Harry). It is also the same stand-in when we see Harry in the behind shots as he holds onto the railings while he tries to climb the steps. (01:14:10)mightymick
Continuity mistake: When Marv and Harry first attempt to break into the McCallister's house, Harry tells Marv to go to the basement, and he goes to the front door. With the front steps covered in ice, Harry slips and falls down the steps, and his crowbar clanks down at the bottom of the first step. When Harry gets up and continues trying to get up the steps and into the house, the crowbar disappears - it is not in his hands.Hawk
Continuity mistake: When the robber with the beard gets hit in the face with an iron, the iron hits him on the face, and leaves a mark slanted to the right. It also leaves a mark on his nose. When the two robbers are talking after they have been tricked and before Kevin puts the spider on one of the robbers, the iron mark is vertical and there is no mark on the nose anymore.