- Ability over Appearance: Kevin Costner is 6' 1", six inches shorter than the real Jim Garrison.
- All-Star Cast: Kevin Costner, Sissy Spacek, Tommy Lee Jones, Joe Pesci, Ed Asner, Jack Lemmon, Walter Matthau, Gary Oldman, Laurie Metcalf, Jay O'Sanders, John Candy, Kevin Bacon, John Larroquette,note Martin Sheen, and others.
- This leads to the odd casting of The Odd Couple without either actor ever interacting with each other.
- The Danza: Jack Martin is played by Jack Lemmon.
- Doing It for the Art:
- Oliver Stone poured his heart and soul into this movie, going out of his way to make sure everything appeared exactly as he wanted it. A great example is his meticulously detailed set of the White House's Oval Office, which cost about $70,000 to complete, yet it only appears in about eight seconds of the film.
- The movie was shot largely on location, including Dealey Plaza in Dallas and the actual book depository where Lee Harvey Oswald (allegedly) shot Kennedy.
- Many actors waived their usual fees to appear in the film.
- Duelling Movies: While JFK was in pre-production, A&M Films announced an adaptation of Don DeLillo's Libra, a 1988 novel about the assassination with many broad similarities to Stone's film, to be directed by Phil Joanou. A script for Libra was written and Jandou began casting key roles, but the project was suddenly abandoned in late 1990, with rumors that Oliver Stone, Warner Bros. or both strong-armed Joanou into abandoning Libra (something Stone has always denied).
- Enforced Method Acting: Garrison begins crying during his closing statement at Shaw's trial. This was because Kevin Costner realized the weight of his character's words, and had an instant emotional response.
- Irony as She Is Cast: Jim Garrison himself makes a brief cameo as Supreme Court Chief Justice Earl Warren, the namesake of the commission investigating the Kennedy assassination and which ended with the official "Oswald acted alone" determination.
- Playing Against Type: One of the few dramatic roles played by John Candy, as a beatnik lawyer connected to the conspiracy. The nervous sweat you see on his face is real, as the thought of acting in a dramatic film opposite such heavyweight actors as Donald Sutherland and Gary Oldman scared Candy shitless.
- Those Two Actors: Subverted. While Jack Lemmon and Walter Matthau are in the film, they don't have a scene together.
- What Could Have Been:
- Harrison Ford and Mel Gibson were Oliver Stone's first choices for the role of Jim Garrison. Also considered were Alec Baldwin, Tom Berenger, Jeff Bridges,note Willem Dafoe, Robert De Niro, Michael Douglas, Gene Hackman, William Hurt, Don Johnson,note Kyle MacLachlan, Michael Keaton, John Malkovich, Matthew Modine, Jack Nicholson, Nick Nolte,note Dennis Quaid, Robert Redford, and Robin Williams.
- James Woods eagerly lobbied for the role of Garrison. However he and Stone had vast creative differences, Woods wanting the film to be more of a biography of Jim Garrison with much more emphasis on his personal life, while Stone wanted it to be primarily about the case.
- Marlon Brando turned down the role of X.
- Dafoe, Jeff Goldblum, Martin Landau, Malkovich and Gary Oldman were considered for David Ferrie.
- Douglas, Landau, Paul Newman, Peter O'Toole and Gregory Peck were considered for the role of Clay Shaw.
- Glenn Ford and Hackman were considered for Guy Bannister.
- Quaid and James Spader were considered for Willie O'Keefe.
- Baldwin, Tom Cruise and Charlie Sheen were considered for Lee Harvey Oswald.
- Danny DeVito and John Goodman were considered for Dean Andrews.
- Harry Dean Stanton was considered for Jack Martin.
- Goldie Hawn and Elizabeth McGovern were considered for Julia Ann Mercer.
Trivia / JFK