The bulk of the monks were played by hippies from a local commune in California.
The gas station attendant out in the desert was a local guy who the filmmakers persuaded to play a small part in the movie.
The majority of this film was shot in various locations without permits.
MUTCD (Manual for Uniform Traffic Control Devices) 1971: Most of the roads traveled by the bikers in the film still have the pre-1971 MUTCD standards (white center lines). However, you will see the odd road that has been repainted in the yellow center line scheme and looks very fresh and half complete. The film was made when the MUTCD 1971 standards had just been released with most painting done between 1972 and 1974.