Twice the project was pitched to television: first, producer David L. Wolper wanted to produce the project as a mini-series, and later, it was being developed as a weekly series by HBO. A pilot that starred Kiefer Sutherland was produced, but the series was not picked up afterwards.
Pierce Patchett's business is based on the long-time rumor that there really was a house of prostitution in Hollywood that supplied ladies meticulously dressed and made up to resemble famous movie stars. In his memoir "Hollywood: Stars and Starlets, Tycoons and Flesh-Peddlers, Moviemakers and Moneymakers, Frauds and Geniuses, Hopefuls and Has-Beens, Great Lovers and Sex Symbols", screenwriter Garson Kanin describes a visit to a place called Mae's where the madam dressed as Mae West and presided over a cast of replicas of Barbara Stanwyck, Joan Crawford, Carole Lombard, Marlene Dietrich and Ginger Rogers, among others.
The closing credits include old footage of famous cowboy star William Boyd as his character Hopalong Cassidy on horseback at a parade. Special effects make it appear that he is marching just in front of the cast of the films fictional police show Badge of Honor.
The shotguns used by the LAPD in this film are Ithaca Model 37s, easily identifiable by the lack of an ejection port on the right side (they eject from the bottom). White and Exley both carry Colt Detective Specials.
Many of the events in the movie were based upon real events. These include the Bloody Christmas scene where drunken police officers brutally beat up Hispanic prisoners suspected of beating up two uniformed cops (the real-life cops involved were named Trojanowski and Brownson -- in the film, they're referred to as Helenowski and Brown); the plot line of real-life gangster Mickey Cohen's arrest touching off a gang war for control of the rackets; the LAPD Goon Squad which would kidnap out-of-town gangsters, beat them up and threaten to kill them if they ever tried to come back to set up their operations; Lana Turner dating gangster Johnny Stompanato (although this movie is set in 1953, and the real Turner and Stompanato didn't start dating until 1957). In real life, Turner's daughter Cheryl Crane stabbed Stompanato to death on April 4, 1958, after catching him beating her mother.
At the end of the opening credits, where you see a copy of Hush-Hush Magazine before Curtis Hanson's director credit appears, the magazine's main cover story is an interview with mob boss Mickey Cohen. The other front page story is Ingenue Dykes in Hollywood. This leads into the scene a short time afterward, when Sid Hudgens, Hush-Hush's editor, approaches Jack Vincennes. Jack introduces Sid to his dance partner, Karen, who walks away. Jack then asks what's wrong and Sid explains "We did a piece on Ingenue Dykes and her name got mentioned."
Mickey Cohen, the mobster who gets locked up which causes the war for control of the drug trade in the story, was a real-life Los Angeles mobster from the late '30s until his death in 1976 after two imprisonments for tax evasion. He was a small-time hood who joined forces with New York gangster Bugsy Siegel when Siegel came to L.A. to run the rackets (see the film Bugsy). After Siegel's murder in 1947, Cohen took over the rackets that Bugsy had built up, including labor union shakedowns at the studios, drug trafficking, gambling and prostitution. He was so hated by the police that he was constantly arrested for any crime, big or small (he was once arrested for using foul language on the street). As shown in the movie, he was eventually imprisoned for income tax evasion and spent nearly ten years in prison. After his release, he was semi-retired from the rackets and lived off his wealth, remaining a colorful character in Los Angeles until his death in 1976.
To pitch the movie to backers (and, later, to explain his aesthetic ideas about it to various cast and crew members), director Curtis Hanson put together a group of 18 period images illustrating different aspects of what he hoped to convey with the movie. These included the "Welcome to Los Angeles" postcard that's in the first shot of the movie. Photos of tract housing, orange groves, and the glamour shot of Veronica Lake are framed on Lynn Bracken's wall. Hanson also chose studio photos of two lesser-known 1950s actors (Aldo Ray and Guy Madison) to show to Guy Pearce and Russell Crowe what he envisioned as models for the characters Ed Exley and Bud White. Exley's model was Madison, while White's was Ray. This film takes its name from "Confidential", a notorious 1950s-era movie star tabloid, which is fictionally portrayed herein as "Hush-Hush".
Some of the close-ups of Guy Pearce's face in the scene where he and Russell Crowe get into a fight were shot four months after principle photography had ended. Much to Curtis Hanson's dismay, Pearce had shaved his head within the time-span and had to wear a wig. During a Q and A session, Pearce referred to it as a "very expensive wig" and noted that in Australia there is no concept of returning to shoot pick-ups weeks or even months later.
James Ellroy describes the character of Bud White as the biggest cop on the L.A. force. Noting that he wasn't even 6 foot, Russell Crowe decided to move into an apartment so small that he had to duck to get into the doorways and could barely stand up in. Crowe said this worked in making him feel like a "giant" by the time he came to the set to shoot.
At the time the film takes place no building in Los Angeles was allowed to be taller than city hall, so the cameras were placed at certain points so that any building taller than city hall would not be seen.
The photos seen during the vice squad briefing were copies of photos taken by fetish artist John Willie during his L.A. period. One of his models was murdered by a serial killer and was mentioned in James Ellroy's My Dark Places.
Warner Bros. was against the idea of casting 44-year old Kim Basinger as a call girl. However, director Curtis Hanson stated that she was his only choice for the part and refused to consider anyone else.
According to Guy Pearce on the DVD commentary, he attended a James Ellroy one-man show in his native Melbourne, Australia while the film was in pre-production. Pearce notes that during a Q&A session following Ellroy's performance, an audience member asked if any of Ellroy's books would ever be adapted into film. Ellroy replied that not only was L.A. Confidential in pre-production, but two Australian natives (Pearce and Russell Crowe) were cast in the film. The audience erupted into laughter, thinking that Ellroy was playing a wry joke on the audience by randomly naming two local actors and claiming they were cast in a big-budget Hollywood film. Pearce, who was sitting in the audience, was mortified. It was only a year later, that the audience learned that Ellroy was, in fact, telling the truth.