Zodiac's confirmed [as of yet] first murder on Lake Herman Rd. was excluded from the film on the basis that there was no surviving victim to corroborate details. In the spirit of accuracy, the crew decided to not include the Lake Herman killings and to instead begin with the July 4th crime, considered to be his second action of murder.
Anthony Edwards was cast as Armstrong because David Fincher wanted him to be played by a thoroughly decent person. Fincher already knew him, not so much from his work on ER (1994), but because he was a neighbor.
Scenes of Dave Toschi and Robert Graysmith watching Dirty Harry (1971) were filmed inside the Mann National Theatre in Westwood, CA. The garish color schemes of the movie theater were not added by the art department. The very retro interiors of the theater have remained unchanged since 1969, when the National was first built. Interestingly, "Zodiac" played at the Mann National Theatre in mid March of 2007. Thus, moviegoers watched other moviegoers occupy their seats - on the National's trademark large screen. The theater has since been torn down.
Dave Toschi in real life was the inspiration for Steve McQueen's performance in Bullitt (1968). In the film, Graysmith mentions that Toschi wears his gun like Bullitt. Avery replies that Bullitt got it from Toschi.
The South Korean film director Joon-ho Bong has classified David Fincher's film as a "masterpiece" writing that "...there was really nothing to find fault with about it, down to the cinematography, art direction and action."
The US Blu-ray released by Paramount Home Video had a very limited run. For a while, the Blu-ray became one of the rarest on the market; fetching prices close to $100 from second-hand online retailers, until Warner Home Video acquired the Paramount catalogue in 2012 and re-released it the following year.
Talks with Sony fell through when the studio insisted that the film should not be any longer than two hours and fifteen minutes. Warner Brothers and Paramount agreed to share the production costs, even though the film was a tough sell being mainly dialogue driven and with an inconclusive ending.
Robert Downey Jr. was so unaccustomed to the experience of both David Fincher's multiple takes and the process of filming digitally that he protested to the director for "having no time to go in my shit together in my trailer" by hiding mason jars full of his urine on set.
The cab scene on Washington and Cherry Streets in San Francisco could not be entirely shot in San Francisco due to filming restrictions and the opposition of the neighborhood residents. So, a set of the intersection, including the street, apartments and crime scene was constructed at Downey Studios just outside of Los Angeles, California. Backdrops of San Francisco were digitally inserted to complete the scene. Only a few seconds of actual footage shot in the original crime scene location remains in the scene.
David Fincher, screenwriter James Vanderbilt and producer Brad Fischer spent 18 months conducting their own research into the Zodiac murders. During that time, they interviewed witnesses, family members, suspects, retired and current investigators, the only two surviving victims and the mayors of San Francisco and Vallejo.
Shane Salerno optioned the Robert Graysmith book "Zodiac" when he was just nineteen years old and developed it with Graysmith for several years before selling it to Disney's Touchstone Pictures in a seven-figure deal. Salerno wrote several drafts of the screenplay before multiple administration changes at Touchstone derailed the project.
This film pays homage to Dirty Harry (1971), whose foe, Scorpio, was based on the Zodiac murderer. Another fictional policeman also encountered a foe called Scorpio around this time. In the Robert Graysmith book, they note that around the time of the Zodiac murders, the police investigated a possible connection to the Dick Tracy comic strip, as Dick Tracy faced a Zodiac-themed gang directed by a mastermind called Scorpio.
Captain Lee tells Toschi to take some time off and "go to Candlestick." Candlestick Park was the home of the San Francisco Giants from its construction in 1960 to 2000, the San Francisco 49ers from 1971 to 2013, and the Oakland Raiders in 1961. In 2014, the 49ers will move to their new home at Levi's Stadium in Santa Clara and Candlestick Park will be demolished.
As Robert Graysmith drives his son to school, the broadcaster on his car radio makes a reference to the then-forthcoming free concert by The Rolling Stones at the Altamont Speedway. It was Melvin Belli's recommendation to the Rolling Stones to hold this particular concert.
The Warner Bros. and Paramount logos used at the start of the film are almost identical to the ones used by the respective studios in 1969, but not completely. In the case of Warner Bros., their 1969 releases did not use their classic shield as depicted here, but instead carried a "Warner Bros.-Seven Arts" logo used when the studio had merged with Ray Stark and Eliot Hyman's production company Seven Arts. As for the Paramount logo, where it would have read "A Gulf+Western company" in 1969, it now reads "A Viacom company," reflecting current ownership.
Variety reported on 6 July 2005 that Gary Oldman had signed to portray attorney Melvin Belli in this film. On 14 February 2006, Gary Oldman's management company, The Douglas Management Group, issued a statement that a story in the Hollywood Reporter indicating that Mr. Oldman acted in the film was not true, and that "Mr. Oldman is not in the film and never was." However, in an interview on 2 March 2007 with Cinematical, the "Zodiac" author Robert Graysmith stated, "Now we had Gary Oldman at one point, to play Melvin Belli. He went to a lot of trouble, they had appliances, but just physically it wasn't going to work, he just didn't have the girth."
When George Bawart is showing Michael Mageau pictures to see if he could identify the Zodiac, the picture to the right of Arthur Leigh Allen (John Carroll Lynch), is Bob Stephenson, the actor who played the Zodiac when he shot Paul Stine.
Though Callahan's Diner was a set built for the film, the Callahan's Diner logo and window script is identical to that used by Callahan's Diner at 1213 Wilshire Boulevard in Santa Monica, California. It's quite likely that members of the cast and/or crew of the film were familiar with the Santa Monica restaurant and used it as an art model for the San Francisco locale. The "Dirty Harry" reference inherent in the Diner's name may simply be an added plus.
Although Toschi and Armstrong are SFPD inspectors, their actual responsibilities are identical to those of detectives in other municipal police organizations. The San Francisco Police Department calls their detectives "inspectors."
Toschi flies to Riverside on PSA (Pacific Southwest Airlines). PSA was one of the first large discount airlines, operating from 1949 to 1988 when it was integrated into USAir. It is not related to Southwest Airlines.
In the flyover shot of the early construction of the Transamerica Pyramid, the "box" foundation is completely devoid of any piles or columns. Unlike most conventional high-rise foundations, the Pyramid was uniquely constructed without any piles driven into the bedrock. The weight of the building actually rests on trusses at the first two levels, and the trusses rest on top of this "box".
The trivia item below may give away important plot points.
When Robert comes face-to-face with Arthur Leigh Allen in the hardware store, the music playing is 'Baker Street' by Gerry Rafferty. As this is Robert's "Sherlock Holmes" moment, this can hardly be coincidental.