In preparation for the role of Charles Manson, Steve Railsback locked himself in a closet for two hours every day.
While the LaBianca house was used in the movie, the Tate/Polanski house was not.
The movie almost was not shown in Los Angeles because network executives were afraid that this would stir up bad memories, especially since this had been only seven years since the murders.
When Steve Railsback received a call to come to Los Angeles to read for the role of Charles Manson in the movie, he auditioned by reading the speech Charles Manson gave in the jury-less courtroom. He had the role three days later.
Much of the dialogue used in the courtroom scenes was taken directly from court transcripts.