The two militant organizations depicted in the film - the People's Revolutionary Strike Force and Uhuru - were modeled after two real-life militant groups, the Symbionese Liberation Army (which kidnapped Patricia Hearst) and the Black Panther Party.
In 1980 a writer sued Clint Eastwood for plagiarism, accusing him of taking the title of the film from one of his works. Eastwood maintained that he was inspired by the Humphrey Bogart film The Enforcer (1951) (which was also owned by Warner Bros). The case was dismissed.
The writers of the original screenplay did not know how to get the script to Clint Eastwood. So they left it at The Hog's Breath Inn, Eastwood's Carmel, California restaurant.
At one point during the movie, a phone call is made from outside Candlestick Park (where the Giants are playing) to a pay phone that is in front of a bridge and a warehouse. The warehouse has since been torn down, replaced by AT&T Park (the home stadium of today's Giants). Fans walking to AT&T Park from the south cross the bridge to get there from the parking lots.
Body count: 13 (plus one man shot in the groin)
The film was originally and unimaginatively called "Dirty Harry III", before officially being titled as "The Enforcer".
The original script was titled "Moving Target", and onward to the working original title "Dirty Harry III", before officially being titled "The Enforcer".
This is the only Dirty Harry film without the music of film composer Lalo Schifrin.
According to director James Fargo, the armed robber inside the liquor store improvised when he booted Harry in the ass.
According to director James Fargo, at Clint Eastwood's request, an improvised bar scene with Tyne Daly and himself drinking in a bar was set up. After drinking four quarts of beer between the two, they managed to get one good line by her saying she had to go pee, which she did, but the scene overall didn't work and was deleted.
The PRSF uses the former Alcatraz maximum security prison to hold the Mayor of San Francisco hostage; at the time of the film's release, Alcatraz was listed in the National Register of Historic Places in 1976. Some of the buildings seen in the film were destroyed during the Native American occupation between 1969 - 1971.
The chess pieces used in the movie was sold from Ingmar Bergman's descendent's estate in 2009 for 1m Swedish Krona (around USD$145,000 at the time).
During the firearms heist (known as Hamilton Firearms in the film) in a warehouse dock, the firearms heisted are real-life infantry weapons in service with the United States armed forces. The firearms include M16A1 assault rifles, Armalite AR18 assault rifles (the AR18 was not adopted as a standard service assault rifle - it was later adopted by the Provisional IRA in Northern Ireland - the villain Tex is seen firing an AR18 during the Alcatraz shootout), and the M72 anti-tank missile, known as the Light Anti-Tank Weapon; in the film, the M72 was called the LAW Rocket. Both the M16A1 and the M72 were used in the Vietnam War.
The third of five movies starring Clint Eastwood as Inspector "Dirty" Harry Callahan.