A scene was filmed with Zelda Rubinstein reprising her role from Poltergeist (1982) (shooting out of a chimney and shouting "Go toward the light!") but was not included in the final cut.
Items from the set are on display at Universal Studios in Orlando, Florida.
This was the first film with a computer-animated title character.
The last name of the Christina Ricci's and Bill Pullman's characters is "Harvey". Harvey Comics is the long time publisher of Casper the Friendly Ghost.
In the breakfast scene, Casper's uncles enter the kitchen twirling like helicopters while Wagner's "Ride of the Valkyries" plays in the background, and Stretch later says "I love the smell of fleshies in the morning!" All this is a direct reference to Apocalypse Now (1979).
A musical scene, deemed too expensive by the film's producers, was scripted and filmed, entitled "Lucky Enough to Be A Ghost" in which the three ghosts sing about their many mental problems during a session with Dr. Harvey, but the animation would have cost a few million dollars.
When Carrigan and Dibbs are trying to get the ghosts out of the mansion, they first try a priest to exorcise them, played by Don Novello as Father Guido Sarducci. When that doesn't work the scene changes to several pieces of furniture being thrown out of the door, and Dan Aykroyd is seen running out. He stops by Carrigan and Dibbs and says, "Who you gonna call? Somebody else." He then leaves quickly. He is dressed as his character, Dr. Raymond Stantz from Ghost Busters (1984) and Ghostbusters II (1989). Both Aykroyd and the Fr. Sarducci character are Saturday Night Live alumni.