The amusement park scenes were filmed inside Old Chicago, the world's first indoor theme park and shopping mall. Built in 1975, closed in 1980, and finally razed in 1986, it was located in Bolingbrook, a southwest suburb of Chicago, Illinois.
A big star like Kirk Douglas was cast as the lead in this film because director Brian De Palma had felt that his previous picture Carrie (1976) had suffered at the box office without a name draw-card.
The scene when agents chase Kirk Douglas from his hotel room is the same hotel and room filmed in The Blues Brothers (1980). Blues Brother John Belushi's brother Jim Belushi makes his debut in this film.
Brian De Palma's second movie featuring telekinesis; his first had been Carrie (1976). Actress Amy Irving appears in both films.
The throbbing vein the psychics have in the forehead whenever they manifest their power was in the original script of Carrie (1976), but was cut from that film due to its limited budget.