This film was originally titled "The Shrine of Ultimate Bliss" and was to co-star Bruce Lee along with George Lazenby, but Lee died about two weeks before filming was set to begin.
During filming George Lazenby suffered an allergic reaction to the shampoo at his hotel and as a result he got the condition alopecia, which caused his hair to fall out.
George Lazenby signed on for this film and two others at a pay rate of $10,000 (US) a week. As it took 22 weeks to make, Lazenby's salary was $220,000 (US), making him the highest-paid martial arts star at that time. Two of his films for Raymond Chow were huge international hits. The Dragon Flies (1975) was the highest-budgeted martial arts film of the era.
This film was originally intended to be the highest-budgeted martial arts/Hong Kong-made film of all time and was to have a wide international release, including in the US. However, when the film's intended star Bruce Lee died suddenly, the film's budget was significantly scaled back and it was given a limited release, which did not include the US. George Lazenby had signed on for the part before Lee died and when the film was still to be a high-budgeted international release.
Shin'ichi Chiba was originally cast to star, along with George Lazenby and Bruce Lee. Chiba flew to Hong Kong in order to meet Lazenby and Lee and to sign his contract. At just about the moment that Chiba's plane was landing in Hong Kong, it was announced that Bruce Lee had died. The original project featuring Lee, Lazenby and Chiba was then changed to feature just Lazenby, as Chiba decided not to appear in the film knowing Lee would not be in it.