Jill Hennessy's twin sister, Jacqueline Hennessy, once played her sister's character during courtroom scenes filmed while Jill was unavailable, due to filming an appearance on Homicide: Life on the Street (1993).
Steven Zirnkilton, who narrates the opening credit sequences, only appeared on-screen once. He played a detective in the pilot episode, Everybody's Favorite Bagman (1990). He had one line of dialogue: "Look at that. Do you believe these guys?".
The distinctive "thunk-thunk" sound effect used in between scenes was created by combining close to a dozen sounds, including that of a group of monks stamping on a floor. The sound is intended to be reminiscent of both a judge's gavel and a jail cell door slamming.
Prior to becoming an actor, Dennis Farina (Detective Joe Fontana) was a Detective in the Chicago Police Department for eighteen years. He got into acting through his former partner and police commander, Chuck Adamson, who had retired and became a police consultant on movies and television shows.
When the show began airing in re-runs on TNT, new digital technology was used to insert "product placements" (paid appearances of name-brand products) into the show. The easiest to spot is for Coca-Cola. Any time you see a Coke can sitting on a desk, it has been added digitally.