There were approximately thirty takes of the scene where producer and director Lindsay Anderson slapped Malcolm McDowell across the face with a script.
After the success of If.... (1968), Malcolm McDowell suggested to producer and director Lindsay Anderson that they should work again. Anderson replied that good scripts don't grow on trees, and that McDowell should consider writing his own if he wanted to give himself a good part. Although McDowell was only thirty at the time, he based this movie around the concept of his own life story, and then brought it to David Sherwin, who then crafted the screenplay.
Virtually every member of the cast played multiple roles.
In France, the title is "The Best of all Possible Worlds", which is the refrain from Voltaire's novel "Candide", upon which this movie is very loosely based.
Lindsay Anderson: As himself, casting "O Lucky Man!" He also appeared in the opening and closing musical renditions of the title song, sitting in the recording studio, and embracing Malcolm McDowell in a scene at the end.