The "hacking"-sequences - the scenes where you see the "inside" of a computer - are mostly motion-controlled models, because director Iain Softley thought that actual computer graphics would look too artificial.
Jonny Lee Miller and Angelina Jolie were married shortly after the making of the film, and then were divorced four years later.
The high school scenes were filmed at Stuyvesant High School in Manhattan, one of a few elite, exclusive high schools for students gifted in math, science and computers. Real school seniors were extras in many scenes. In the real school, the pool is on the first floor.
The computer they break into is a fictional mainframe computer called a "Gibson" - a homage to cyberpunk author William Gibson.