The Courtroom scenes were filmed in the Wayne County Commission (Detroit) meeting room and most of the extras were Commissioners, their staffs, and County workers.
The word "fuck" and all various permutations of it are uttered 153 times.
Cameo: [Tim Burton] one of the corpses in the Teamsters' funeral scene.
In the part of the film where Hoffa (Jack Nicholson), Bobby (Danny DeVito), and Delasandro (Armand Assante)have their meeting out in the woods. The scene begins with Bobby sitting in a woody wagon and placing an empty beer bottle on a post before driving down to meet Hoffa. In a scene that followed, but was cut, Bobby gave Delasandro a hunting rifle. Delasandro then tried and failed to shoot the beer bottle off of the post. Hoffa then shoots the bottle off in one shot, upstaging Delasandro.
In the film, Robert Kennedy declares during the hearing "If Mister Hoffa is acquitted... I'll jump from the capitol dome!" In a scene that followed, but was cut, Hoffa and the others celebrate his acquittal by eating a cake shaped like the US Capitol Building and featuring a figurine Robert Kennedy jumping from the dome with a parachute.
With the exception of the exchange between Jimmy Hoffa and Robert Kennedy when Hoffa first enters and delays the start of the proceedings, virtually every word between Jimmy Hoffa and Robert Kennedy is taken verbatim from the transcripts of the hearing. A portion of that hearing is included in the Special Edition DVD.
Jack Nicholson's daughter plays the young nun in the hospital scene where Billy Flynn is dying from his burns. According to Danny DeVito in the DVD Commentary, Nicholson had asked him to give his daughter a small part. At first, Danny DeVito suggested she play the hooker in his hotel room in a later scene, drawing the trademark raised eyebrow from Nicholson. Since DeVito was joking he, of course, relented and cast her as a nun.