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: In the first film, it is mentioned several times that Kevin is 8 years old. However, in this film it is stated that he is 10. When his parents are in the Miami airport security office, they say that he was left alone last Christmas. That would make him 9. Both films take place the same days, from about three days before Christmas until Christmas morning, so even if Kevin is born around Christmas time this is still a mistake.