Anachronisms: The overhead shots of the San Francisco taxi show Bus Only lanes with a diamond symbol. While there were Bus Only lanes at the time, the diamond symbol was not used until many years later.
Incorrectly regarded as goofs: In the store there is a calendar behind the desk that indicates it is February 1980. However, as Graysmith is entering the store, the caption says it is Dec. 20, 1983. The prominent out-of-date calendar may just be a way of showing that the store that Allen works in is a sleepy place where they've forgotten to change the calendar for four years.
Factual errors: The blood-stained fabric from the taxi driver should not have been red. The iron in the blood would have turned brown due to oxidation.
Anachronisms: In the scene where the motorcade drives Melvin Belli down Division Street to his meeting with Zodiac, the modern San Francisco skyline is visible.
Continuity: When Robert Graysmith is in Paul Avery's house after he is retired from the Chronicle, the score is 15-9 on the screen displaying Pong. However, another shot is taken and the score is 14-9, but instantly changes back to 15-9.
Anachronisms:Chloë Sevigny's character orders penne ala vodka, but that dish wasn't invented until the mid-70s and wouldn't have made its way to an inexpensive San Francisco restaurant until much later.
Anachronisms: The computers shown in a scene from the early 70s were DEC computers made in the early 80s.
Anachronisms: The color of the United Airlines airplane was incorrect in the 1991 scene. At that time, United Airlines planes were white with orange, red, and blue stripes. The colors that were on the plane featured in this scene had not been used since 15-20 years prior to it taking place.
Factual errors: The interior of the PSA flight boarded by the detectives and Paul Avery reveals 5-across coach seating, standard fare for a DC-9, a popular airplane in the 1960s-1970s. The lady seated behind David, however, is holding a safety card reading "727-200," an airplane which seats 6-across in coach.
Anachronisms: The interior of the PSA flight boarded by the detectives and Paul Avery has the current United Airlines blue-and-orange design on the rear bulkhead.
Anachronisms: Although the choice of a mid-fifties Crown bus was correct for the Napa Valley School District at the time, the bus was showing a California passenger car license plate instead of the correct "Exempt" government plate.
Factual errors: In the scene aboard the PSA flight to southern California, the flight attendant makes an announcement over the speaker stating that "smoking is allowed only in the last six aisles." No airplanes have six aisles; presumably she meant to say "the last six rows."
Continuity: Robert Graysmith follows Robert Vaughn's car to Vaughn's house in the pouring rain. Vaughn lets Graysmith in his house, offering to hang up Graysmith's wet jacket. Graysmith politely but hurriedly refuses. Next, Graysmith enters the kitchen and sits at the dining table, his back to the camera. His jacket is now dry.
Miscellaneous: Actors in the film pronounce "Vallejo," the name of the town, the way outsiders tend to - they assume it's "Vuh - lay - ho." Locals, however, which would definitely include police and even San Francisco reporters, pronounce it "Vuh - lay - o."
Anachronisms: When entering the TV station where Melvin Belli is to receive a phone call from Zodiac, a modern ABC 7 logo can be seen on a sign on the exterior of the studio.
Anachronisms: In the scene where Avery is meeting someone in an abandoned building, and in the following scene where Graysmith and his date race to telephone Avery, a traffic signal in the background shows pedestrian control beacons of the "hand/man" style, rather than the "walk/don't walk" style of that era.
Anachronisms: One of the books Robert Graysmith has in 1969 has a barcode on the back. Barcodes were not in commercial use until several years later.
Errors in geography: The scene where Melvin Belli is to meet the Zodiac impostor at St. Vincent De Paul's Thrift Store in Daly City is actually filmed on the corner of 26th Ave. and Irving Street in San Francisco's Sunset District. In the background, the Sunset Supermarket can be seen, which did not have Chinese characters displayed at the time the movie took place.
Errors made by characters (possibly deliberate errors by the filmmakers): Graysmith says he is an "Eagle Scout, first class." There is no such award as Eagle Scout first class. There is a rank of First Class in Boy Scouting, but it is much lower than Eagle.
Continuity: Interior shots of the gold '63 Corvair contain errors. Some are shot in a two-door coupe and others are shot in a four-door sedan model. In one shot, the door-lock button for the rear door can be seen. And the rear-side window profile is distinctly different from one shot to another.
Anachronisms: In the scene where Graysmith decides to drive his son to school instead of letting him ride the bus, a 1971 Chrysler Newport can be seen parked at the curb behind the bus. The scene is set on October 1969.
Audio/visual unsynchronized: When Robert Graysmith visits Paul Avery at his boathouse, you can see "Pong" on Avery's TV. As the scene plays out, you can hear the Pong ball bouncing around for a while, then the sound of the ball scoring. But it's the same shot of the ball bouncing once, then going past the paddle on the right and scoring.
Factual errors: When Robert Graysmith visits Paul Avery at his boathouse, you can see "Pong" on Avery's TV. If Avery had been playing the game in one-player mode, the paddle on the right would have been controlled by the computer, and it would have been moving to block the shot. Moreover, 15 is the game point on "Pong." Once this is reached, the ball disappears until the game is reset. If it is left on for a long enough time, it will go into the Demo mode. But in Demo mode, there is no sound.
Anachronisms: The overhead shot of downtown Sacramento in early the early 1970s shows the roof of the Hyatt on 12th and L. The Hyatt was not built until 1988.
Anachronisms: Until the 1980s, Riverside Community College was referred to as Riverside City College.
Revealing mistakes: At the end of the movie, we see a ramp shot of the Ontario (KONT) California airport in 1991. The United Airlines 727's parked on the Ramp are all painted in a paint scheme that was changed in the mid 1970's.
Continuity: In the bar where Paul Avery and Robert Graysmith have their first drink together, Avery's glass sits to his left in some shots; and in others, it sits to his right, next to Graysmith.
Errors in geography: During the time-lapse sequence of the building of the Transamerica Pyramid, light shines from the west as the sun rises.
Continuity: During the TV station interview with Melvin Belli, the SF coffee mug moves by itself in between shots, periodically showing either the front or back design.
Anachronisms: On the evening of her abduction on March 22nd, 1970, Kathleen Johns is shown driving down Highway 132 while Lynn Anderson's "Rose Garden" is playing on the radio. "Rose Garden" wasn't recorded until September 10th, 1970 and wasn't released as a single until October 8th, 1970.
Anachronisms: The Karman Ghia has California license plates with a blue background. Since this scene is supposed to take place in 1969, the license plate should have been the older style, which had a black background.
Anachronisms: In one of the 1970 scenes, Melanie (played by 'Chloe Sevigny') orders penne alla vodka. Unfortunately, while the exact invention of the dish is still disputed, the earliest possible record is at Orsini's in New York City as "penne alla Russia" in 1972. And Williams Sonoma's Essentials of Italian Cookbook claims it wasn't created until the early 1980s.
Continuity: When Inspector Toschi hands Arthur Leigh Allen's watch to Inspector Armstrong, the time jumps ahead about 2 minutes instantly. Also during the hand-off, the bezel rotated about 40 seconds counter-clockwise, as shown by the black indicator marking.
Revealing mistakes: When the Zodiac hails Paul Stine's cab, an illuminated hair salon sign is visible on the other side of the street. However, the reflections seen on the cab's hood and trunk lid are of the modern-day Starbucks Coffee sign at the filming location which was digitally removed in post.
Incorrectly regarded as goofs: Graysmith and Arthur Leigh Allen both refer to "The Most Dangerous Game" as a book or a novel. It isn't; it's a short story. However, it is entirely possible that the characters only refer to it as such because are subconsciously simplifying their language in conversation with others.
Continuity: When Graysmith looks at the print out of Allen's driver's license his middle name is spelled "Leigh". But when Graysmith goes to the convenience store to see Allen the name on his shirt is spelled "Lee". (This may have been intentional, as someone preferring the name of Lee would gave been more likely to use the conventional spelling.)
Anachronisms: In the overhead shot of Sacramento, besides the 1988 Hyatt Regency being depicted, there is also the Capitol Park "East End" State Office Complex shown at the bottom of the frame, which wasn't built until 2000.
Factual errors: The taxi driver picks up his murderer on Geary St. in the theatre district. As the camera follows overhead, trolleybus power lines are visible. However, Geary St. did not have trolleybuses, so the power lines are appear in error. The 38 Geary bus route, one of the longest in San Francisco, was always a diesel route.
Errors made by characters (possibly deliberate errors by the filmmakers): When Zodiac is "fixing" Kathleen Johns' wheel, he is seen in the mirror twisting the wheel nuts clockwise, as if to tighten them (which he was supposed to be doing), but if the wheel were to fall off, he should have been twisting anti-clockwise to loosen the lug nuts.