Number 666 references: the building number is 333 (666/2), the elevator number is 6, and stops on floors 23 to 42 (2*3=6, 4+2=6)
In its first weekend of release in the United States it was able to gain back its entire production budget.
In some theaters, the staff would play a prank on the movie goers where the opening credits would role, but the movie would then stop playing and the screen would go completely dark. Elevator music would then begin to softly play, and then the movie would start up again. The movie goers would think this was part of the film.
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.