The One Thing You’ve Probably Never Noticed in ‘Home Alone’ That Will Change How You See the Movie

That crucial scene may explain why the family never noticed Kevin was missing from the flight — they didn’t have his ticket.

An IMBD answer explains more:

Q. Why didn’t they notice Kevin’s absence when they presented his airline ticket at the boarding gate?

A. Kevin’s ticket was tossed in the trash when his father wiped up after Kevin spilled milk all over the passports and tickets. While getting into the car to go to the airport, Heather miscounted because the neighbor kid was in line with the rest of the family. Finally, the gate agent appears to be simply counting the McCallisters’ tickets instead of matching names with people. Without a ticket for Kevin, no one apparently noticed that he was not in the group.