The scene where Billy sees Jenny's body distort in the shower was added during the production because Yuzna felt the film needed another shocking scene earlier in the film.
Writer Woody Keith came from a Beverly Hills family much like that of Bill Whitney and many of the characters depicted in the film are based upon real people Keith knew in Beverly Hills.
The scenes where Billy has therapy sessions with Dr. Cleveland weren't in the original script. They were added during production to help strengthen the narrative of the movie.
The original script began with the scene where Billy creeps back into his house after leaving the hospital, with the first hour of the film being told as a flashback. To avoid audience confusion though Brian Yuzna opted instead to have a new opening wrote that's more of a foreshadowing to later events rather than setup for a flashback.
A dozen crew members were used to work the large, contorted puppet for the 'shunting' finale. The puppet was moved from beneath the stage floor where the crew members were concealed.
The shot of Clarissa contorted in bed was achieved using Devin DeVasquez and one of DeVasquez's friends, who was buried under the covers with her legs exposed. The two were placed at such an angle that it appears to be Clarissa's body twisted in a strange position.
During Ferguson's party Milo is seen wearing a shirt that says 'eat the rich' on it. The shirt belonged to Brian Yuzna and was a left over memento of his college days.
The trivia items below may give away important plot points.
The original script had a different finale where the secret society was revealed as a cult that was out to sacrifice Billy for their own crazy reasoning. Brian Yuzna however wanted a much more fantastic revelation for the film so he and makeup artist Screaming Mad George came up with the idea of the society being monstrous creatures that ate the lower class.