!!The 1987 movie
* ActorInspiredElement: It was Creator/SeanConnery's idea to film the "blood oath" scene between Ness and Malone in a Catholic church. Originally it was going to take place on the street (in the same scene that follows the church scene). Connery felt that a church would be the only "safe" place in Chicago where the two characters would make such a commitment to fight Capone.
* CaliforniaDoubling: The Canadian Border raid was filmed at Hardin, Montana, which is about as far away from the Canadian border as you can get while still being in Montana.
* CompletelyDifferentTitle: In Sweden, the film was called "De omutbara", meaning "The Unbribable [Ones]".
* DyeingForYourArt [=/=] MethodActing: Creator/RobertDeNiro gained 30 pounds for his role as Capone, and (allegedly) even insisted on wearing the same clothes Capone did, right down to his silk underwear.
* EnforcedMethodActing: For his death scene, Creator/SeanConnery did not expect the squibs to be as explosive as they were. After the first take, he was taken to the hospital with dust and fake blood in his eyes.
* FakeIrish: Edinburgh-born Creator/SeanConnery as Jimmy Malone.
* FakeNationality: Havana-born Creator/AndyGarcia as an Italian-American (first generation), and the Kansas-born Native American and Romany Billy Drago as an Italian.
* StarMakingRole: For Creator/KevinCostner and Creator/AndyGarcia.
* ThrowItIn: Creator/KevinCostner ad-libbed the line "He's in the car," after [[spoiler:throwing Nitti off of the roof]].
** Creator/MelGibson turned the role of Eliot Ness down in order to star in ''Film/LethalWeapon''. Creator/HarrisonFord, Creator/MickeyRourke, Creator/MichaelDouglas, Creator/JeffBridges, Creator/NickNolte, Creator/JackNicholson, Creator/WilliamHurt, Creator/TomBerenger and Creator/DonJohnson also passed on it.
** Suffolk-born Creator/BobHoskins was cast as UsefulNotes/AlCapone, but was paid a bundle of money once Creator/BrianDePalma brought Creator/RobertDeNiro, the director's first choice all along, onboard.
** Creator/GeneHackman was offered the role of Malone.
** In the original script, the final gunfight had Eliot Ness and George Stone battling Capone gunmen on a stopped train. Creator/BrianDePalma conceived the gunfight on the steps in Chicago's Union Station when Paramount decided that staging the scene and finding a 1930s period train would be too expensive.
** There was originally a different ending for the movie. It was to have been a scene with the camera shooting a close up of Capone's face as it is being warmed up for a shave. And then the camera would have craned up to show the audience that he has reporters around him, but he is in his jail cell.
** Cinematographer Stephen H. Burum originally wanted to shoot the film in black & white.
* WritingByTheSeatOfYourPants: Creator/BrianDePalma said that when he was filming the scene in the train station, he made up the series of shots as the scene was being filmed.