'William Hurt' wanted to play the role of Paul Maclean and once went fishing with Norman Maclean in Montana. When Hurt asked if he'd fished well enough to portray his brother, Maclean replied: "Well, Bill, you're a pretty good fisherman but not good enough to be my brother."
Trout used in the movie were pond-raised in Montana and were kept in a specially aerated and cooled tank truck until their big moment in front of the cameras. No hooks were used, and no blood was drawn. A line was tied to each fish's lower jaw under the careful observance of the Montana Humane Society.
Even though the film claims that it is filmed in Missoula, it is actually filmed in and around Livingston, Bozeman and Big Timber, Montana. Many of the fishing scenes were filmed in the Gallatin Canyon on the Gallatin River south of Bozeman.
George Coonenbergs was a retired railroad engineer. He taught Brad Pitt, Craig Sheffer and Tom Skerritt how to fly-fish for this movie. He also taught fly-fishing and fly-tying to his fellow residents, and staff members, of his retirement community. He grew up near the Maclean family in Missoula, MT. His family's cabin was built next door to the Maclean family cabin in Seeley Lake, Montana. He learned to fly fish and tie flies from Rev. John Maclean, and was considered Paul Maclean to be his best friend. The friendship between the Maclean and Coonenbergs families continues to this day, into its fourth generation.
Elmer Bernstein wrote the original score for this film. However, it was rejected by director Robert Redford and so Mark Isham composed a new one. Interestingly enough, Bernstein's name remained in the film's opening credits as the composer.
Norman Maclean often recounted the story of how his semi-autobiographical story collection was rejected by every large commercial publisher he sent it to, including one that rejected it on the basis that it contained "too many trees." It was eventually published instead by the University of Chicago Press (in 1976) and went on to sell extraordinarily well for them.
The film was originally produced by Carolco, the studio responsible for Terminator 2: Judgment Day (1991) and the "Rambo" films, among others. Due to the serious debt Carolco was facing, Robert Redford called upon film producer Jake Eberts to put in the financing of the pre-production. During post-production, Carolco sold their rights to the film to Eberts.