: Megastar Paul Newman was initially expected to play the Sundance Kid, with Steve McQueen cast as Butch Cassidy. After McQueen backed out due to billing disputes, Newman swapped to the role of Butch.

The film's script, written by William Goldman, was also a major factor in its success. The script was witty and engaging, with memorable lines like "Who are you?" "I'm Butch Cassidy." "And I'm the Sundance Kid." The film's dialogue was full of clever one-liners and humorous exchanges, and it helped to humanize the outlaws, making them more relatable and sympathetic characters.