Nicolas Cage recorded all of the inner monologue at a local recording studio before shooting began. He was fed the audio on set.
The "plastic" spoon stuck to Nicolas Cage's lapel was actually a metal spoon that had been painted to appear plastic and which was held in place with a magnet.
The Naperville Central High School marching band was asked to be in that parade, and the song they are playing is their school's fight song.
Tom Skilling, WGN and Chicago Tribune Chief Meteorologist, is a technical advisor and makes a cameo appearance as the TV station floor director.
Despite Paramount Pictures suggesting that the production be shot in Canada, to substitute for Chicago, Gore Verbinski and Nicolas Cage both insisted that the film be shot in Chicago for authenticity.
While shooting the film in February, director Gore Verbinski was surprised to find that the weather in Chicago was warm, as it didn't produce any snow. The production designers had to recreate snow from scratch, as the film takes place during the winter season.
The film that Mike is watching while his parents are fighting is "Clear and Present Danger".