In this movie, Bruce Lee's character is shot with a prop gun that was secretly made to fire a real bullet and kill him. Lee's son, Brandon, was killed on the set of The Crow (1994), when a prop pistol accidentally shot him in the abdomen.
Bruce Lee had filmed over 30 minutes of fight scenes for this film when work was suspended to allow Lee to work on Enter the Dragon (1973). However, Lee died before he could return. Six years later, director Robert Clouse fleshed out a feature around the original footage with a new cast, including two stand-ins for Lee, who faces are hidden by dark sunglasses and shadows. Close-ups and stills of Lee's face (including a cardboard cut-out) were also used.
Hapkido Master Ji Han Jae, who plays the second guardian 'Bruce Lee' battles in the Pagoda/Restaraunt, gets no screen credit in the 1978 version of the film. A strange omission considering his substantial role in the original shoot.
George Lazenby was originally meant to be in this film and was due to meet Bruce Lee on July 20 1973, the day Lee died. For other reasons, Lazenby was not involved in the final project as directed by Robert Clouse.
Sammo Hung almost didn't appear in the movie; after being asked personally by Bruce Lee to be part of the film, Hung waited for eight months without follow-up and eventually went to film projects in Korea and Thailand, only flying back to the set in China when promised that it would only take a couple days to film his part.
The inspiration for progressively ascending a pagoda tower to fight opponents was originally featured in Chang Cheh's swordplay epic 'Bao Biao (1969)' aka 'Have Sword Will Travel' written by resident Shaw Brother screenwriter Kuang Ni.