David Allan Coe, who plays Whiskeyhead Ryan, is also a country singer. He covered Guy Clark's hit 'Desperados Waiting for a Train', which was also a hit for the Highwaymen.
The film features three of the four members of the country music super-group "The Highwaymen": Johnny Cash, Kris Kristofferson, and Willie Nelson. The only one not featured was Waylon Jennings.
In the film, June Carter Cash plays the mother of Frank and Jesse James, played by Johnny Cash and Kris Kristofferson respectively. In real life, Johnny Cash and June Carter were husband and wife.
In reality Jesse James was only 34 when he died.