Butch Cassidy + the Sundance Kid connection
I have not watched this movie but as soon as I saw the names of the two lead characters -- Mr. Parker and Mr. Longbaugh -- I thought of the two famous outlaws. Butch Cassidy was the alias for Robert Leroy Parker, and the Sundance Kid was the alias for Harry Longabaugh (sometimes misspelled by historians as Longbaugh). After I read at one of the message board topics that there was a shootout at the end of the movie and that it wasn't clear whether or not Parker and Longbaugh died then I knew that the Newman/Redford movie and the real and/or fictional accounts of Cassidy & the Kid provided some inspiration for "The Way of the Gun".