Incorrect goof
The goofs section has this:
"While trying to get his bag into the compartment, a man tries to push past Greg, which causes him to yell "where's the fire?" Annoyed, the passenger sits in the seat in front of him. However, when Greg is being dragged out of the plane you can clearly see the same man sitting in the seats in the terminal, as though he had been there all along."
This isn't a goof--those are all the people who were on the plane with Greg. It is assumed that as soon as Greg told off the flight attendant, she called for security and they boarded the plane and told everyone to exit the plane while they dealt with Greg. Since he presumably refused to go and was acting loony, they dragged him off the plane.
Also, since it's 2:35 AM and the airport is empty, those people in the airport chairs are not customers who are waiting to board a different plane because the time from Greg boarding the plane from an empty airport to being dragged off is only about 5-10 minutes.