Bruce Lee wasn't actually meant to be in Fist of Unicorn. He was only there doing action choreography as a favour to long-time friend, Little Unicorn. The enterprising producers filmed Bruce Lee working, and edited the footage into the film. Lee was reportedly less than impressed.
In 1972, Bruce Lee's star was rising faster than anybody could have imagined. In the midst of all this, Unicorn Chan, Lee's long time friend and confidant was offered a leading role. Lee offered assistance to the man who helped him get back into the Hong Kong film business. The result was "Fist of Unicorn", the only film outside his own that Bruce Lee would action-direct and help promote. Apart from Unicorn, they are many co-stars from the Lee's films also.in this film.