Sleeper Hit: Warner Bros. thought that the film would bomb, feeling that nobody would want to cheer for the outlaws in a gangster flick, and dumped it in August and offered Warren Beatty 40% of the gross as a result. Upon release, the mixed critical reception seemed to bear out their fears. But when young people started raving about it to everybody in earshot, it turned into one of the biggest films of 1967, and remains a classic.
The writers of this film originally hoped to they could get either of the great French New Wave directors to helm this film, François Truffaut or Jean-Luc Godard. Unfortunately after helping develop the script, Truffaut ultimately decided to direct Fahrenheit 451 instead and Godard turned out to be an unreasonable jerk when the producers were courting him. So Arthur Penn, whom Truffaut had recommended, did it instead.
Warren Beatty once considered Bob Dylan for the role of Clyde.
Natalie Wood, Warren Beatty's ex-girlfriend (one of many actually), was considered for the role of Bonnie - and incidentally was actually a lot closer to the real Bonnie's physicality (they were both short ladies).
Bonnie and Clyde were originally supposed to have a bisexual relationship with their driver, but that was changed when Arthur Penn felt that would have defused the audience sympathy, leading them to be dismissed as "perverts" because they are criminals and ultimately harmed the story. There were also rumors that Warren Beatty was unwilling to portray a bisexual and ruin his image and there was the fact that The Hays Code would never have permitted it in the film in the first place.