Legend has it that Dylan scrawled the opening lines on a napkin and said, ‘Give it to McGuinn, he’ll know what to do with it.’ After viewing a private screening of the film, Dylan demanded that his name be removed from the songwriting credit–either b/c he didn’t like the movie, and/or he didn’t want his name to be used to give the film street cred:
The Byrds recorded the song later in 1969: