At the beginning of the movie; a person is seen falling from a top floor high-rise. Pushed, thrown or jumping, his is highly unlikely. The exterior windows (those from floor to ceiling, or those that replace traditional exterior walls) would be triple plated, like that of a bank partition (think of 3 car windshields glued together) One would have to repeatedly bang on it with a sledgehammer before it would even crack, let along jump clean through.
All five characters who get on the elevator have the color red in common: the Mechanic's satchel, the Old Woman's hair, the Young Woman's nails, the insignia on the Guard's uniform and the Salesman's tie are all red. M. Night Shyamalan is known for having red as a prominent feature in his films.