The film's famous chase scene wasn't originally in the script. In the first draft of "Bullitt", adapted from Robert L. Pike's novel "Mute Witness", Det. Frank Bullitt was a Boston policeman who ate a lot of ice cream and never solved a case. The book had originally been bought with Spencer Tracy in mind; but with Tracy's death, the property fell into the hands of Steve McQueen and Producer Philip D'Antoni. D'Antoni added the chase and changed the location to San Francisco.
The holster worn by Steve McQueen was later put into production by Safariland leather company and is still in the line. It is known as the Klipspringer Shoulder holster.
The license plate on the Mustang is JJZ 109.
The Mustang's interior mirror goes up and down depending who is driving it - Steve McQueen (up, visible) or Bud Ekins (down, not visible).
This film is edited entirely by cuts except in two instances. The first occurs when the jazz club scene dissolves to a shot of Steve McQueen lying in bed. The second occurs after the Dodge crashes into the gas station and burns, when the shot of the two dead villains dissolves to a scene at the police station.
Two Mustangs and two Dodge Chargers were used for the famous chase scene. Both Mustangs were owned by the Ford Motor Company and part of a promotional loan agreement with Warner Brothers. The cars were modified for the high-speed chase by veteran auto racer Max Balchowsky. Stunt coordinator Carey Loftin got Bud Ekins to drive the Mustang for the bulk of the stunts. Both of the Dodges were junked after the filming, as was one of the Mustangs. The other less banged-up Mustang was purchased by a WB employee after all production and post-production was completed. The car ended up in New Jersey a few years later, where Steve McQueen attempted to buy it. The owner refused to sell, and the car now sits in a barn and has not been driven in many years.