In this film, when Linda tells Bruce that she's pregnant for the second tine, a musical band is visible in the background. The lead singer of this band is played by Shannon Lee, Bruce Lee's real-life daughter.
In this film, the director of the television series El avispón verde (1966) was played by Van Williams, who actually played the leading role of Britt Reid in the series.
Jason Scott Lee had no previous martial arts training or experience, but was an accomplished dancer. He was selected for the lead because it was thought a dancer would more accurately depict the way that Bruce Lee moved. He was trained especially for this role, and had numerous stunt doubles.
Dedicated to the memory of Bruce Lee's son Brandon Lee, who died (March 31, 1993) due to an accidental shooting on the set while filming El Cuervo (1994).
When Bruce Lee is preparing to fight the martial artist chosen to stop him from teaching the "Guai Lo", their warmup is obviously derived from El dragón (1972): Lee is exercising his flexibility, while his opponent, like Chuck Norris, is instead practicing a series of "rehearsed routines."
Rob Cohen: after Bruce Lee finally defeats the demon, and is back on the set of Operación dragón (1973), the director says, "Lost you for a minute there."