- B-Team Sequel: Don Siegel declined to return as director. Clint Eastwood considered directing it himself.
- Creator Backlash: John Milius later said he did not like the film and wished Don Siegel had directed it, as originally intended:Of all the films I had anything to do with, I like it least. They changed a lot of things in a cheap and distasteful manner. The whole ending is wrong, it wasn't mine at all. All movies had a motorcycle or car chase at the time except Westerns. They have a scene where this black girl's pimp forces Drano down her throat. In the script, they merely went into the morgue and Harry said, "I don't feel bad for that son of a bitch, 'cause two weeks ago one of his girls was in here and he'd poured Drano down her throat." I think it's better to hear about it than to see it later; also, it goes right back to the character again: you understand Harry's feelings about it. All the stuff they put in about the Japanese girl: they put in a scene where the star gets to fuck some girl, and it's pretty hard to get it out. My Dirty Harry scripts never had Harry knowing any girls too well other than hookers, because he was a lonely guy who lived alone and didn't like to associate with people. He could never be close enough to a woman to have any sort of affair. A bitter, lonely man who liked his work.
- Creator's Favorite Episode: This is Clint Eastwood's favorite Dirty Harry film.
- Deleted Scene: Two deleted scenes help explain why Harry grows to suspect John Davis and his pals with the killings of Charlie McCoy and the mobsters. One occurs between the funeral flight for McCoy and the combat championship; after the flight Harry and Davis drive from the airport to a bowling alley for a few drinks; a black youth is suddenly chased outside and assaulted by four toughs; Davis attacks the toughs while Harry dispatches one with his beer mug. After subduing the robbers Davis harangues a group of eyewitnesses for letting such crimes take place; Harry witnesses Davis' harangue and sees in it his own approach to crime fighting, albeit far more severe. Later, after examining the bullet from Davis' gun at the combat championship range, Harry checks on old issues of a police magazine, in which are articles condemning the revolving door justice allowed by liberal politics - articles authored by the four rookie cops. These scenes were deleted presumably because they were judged to be "padding" and not necessary to establishing Harry's suspicion of the four rookie cops.
- Life Imitates Art: On April 22, 1974, 2 men robbed a HIFI shop in Ogden Utah and made the 5 hostages drink Draino and then shot them in the head. The next day an unnamed informant called in a tip to Ogden City Police with information that would help wrap up the case much sooner than police had anticipated. The informant, an airman stationed at Hill Air Force Base, told police that he had overheard two of his fellow airmen talking about robbing a store and killing witnesses utilizing the Death By Drano method by which the Pimp murders the Prostitute, which the two had seen prior to the Crime. Two of the hostages miraculously survived. The crime would forever be known as The Hi-Fi Murders.
- Refitted for Sequel: The idea of the main villain killing criminals who escaped justice was taken from Terrence Malick's draft for Dirty Harry.
- Wag the Director: Clint Eastwood apparently took over a lot of the directorial duties after the director that they originally hired turned out not to be up to the job.
- Working Title: Vigilance.
Trivia / Magnum Force