Even on the special features of its own DVD, The Silent Flute, released in the US under the nonsensical title "Circle of Iron", is controversial. Developed by Bruce Lee, James Coburn and Stirling Silliphant as a project for Lee, and eventually made after his death with David Carradine and Jeff Cooper.
It was intended as a Zen parable and not an action movie, although one assumes the intention of the title change was to suggest otherwise. It takes place in no-land. The place of story rather than a literal earthly place. The actions of the characters are not to be taken or understood as literal.
Looking at varying reviews, there is much criticism, especially of Jeff Cooper's performance in the lead. I can't say that I entirely disagree with what they're saying, but then I'm not sure the movie would actually work better if, y'know, worked better. Maybe I'm wrong.
It certainly is an interesting little movie as it is, and Carradine is an absolute delight in all four of his performances.