During the filming of the fight sequences, David Carradine's nose was broken twice, his toe gouged, and knee hurt.
When Bruce Lee was slated to star, he met with Roman Polanski in Switzerland in the hope that he might direct.
David Carradine was originally offered the part of the main character Cord, but preferred the multiple roles intended for Bruce Lee.
According to a recent biography of Bruce Lee, this movie was intended to be shot in 1969, with Lee playing the four roles of The Blind Man, Monkeyman, Death, and Changsha, and the lead role of Cord was offered to Steve McQueen. McQueen, however, turned down the role after remarking that he wasn't prepared to make Lee a star, and instead it was offered to James Coburn. Disagreements over location shooting (Lee preferred India) led the movie to be abandoned until after his death, when the rights were acquired by David Carradine. Originally, karate champion Joe Lewis was offered the role of Cord, but declined, as he was unwilling to work with Carradine. Jeff Cooper, a friend of Carradine's, finally took the part, and Lewis ended up supervising the re-shooting of some of the fight scenes.