There were often arguments between Bruce Lee and Raymond Chow, one ending with Lee storming off the set. Lee felt that Chow was trying to assert himself as the mastermind of the movie, and that he wasn't being kept informed of everything going on in their partnership, while Chow thought that business was his side of the partnership and that he didn't have to consult Lee on every decision and told Lee to get on with the acting.
Fights broke out onset between stuntmen and extras hired from rival families of Triads.
When the extended Cantonese/Mandarin versions were released for the first time in English in 1998, some extra dubbing had to be done, because no English dialogue existed at that time for those scenes. One of the scenes involved Roy Chiao (Shaolin Abbott) and Bruce Lee. Chiao was still alive (he died shortly thereafter), and was able to dub himself, but Lee's voice was supplied by Bruce Lee biographer John Little. Luckily, Lee's real voice was left alone for the scenes that originally used it.
The Other Marty: Jim Kelly replaced Rockne Tarkington, who quit the film three days before production was due to start because he thought the pay was too low.
Throw It In!: In the scene where O'Hara (Robert Wall) is beaten by Lee, Lee delivers a flying kick to O'Hara. Wall and Lee had decided that Lee should deliver a real flying kick to add authenticity to the scene, as Wall knew how to take the hit. They had not planned for Wall to go flying back into the extras, knocking them all over and actually breaking one's arm.
Unintentional Period Piece: The leisure suits, turtle necks, the funky music, Williams' afro and manner of speech along with mentioning that the Vietnam War was only a few years ago, all point to this movie being in The '70s. Also, this movie is mostly responsible for kick-starting the kung-fu craze in the US during this time.
Vacation, Dear Boy: Ahna Capri told her agent she wanted to film a movie outside of Los Angeles. He called back and told her about this movie. She was on a plane to Hong Kong that night.
Rod Taylor was originally considered for the role of Roper, but he was thought to be too tall compared to Lee, with whom he would have been sharing many action scenes.
As noted under Executive Meddling, the original script had Roper die and Williams survive to the end. The reverse happens in the film.
Working Title: Warner Bros. wanted to call the movie Han's Island because they thought international audiences would be confused by an action movie titled Enter the Dragon. Other alternate titles were Blood and Steel, this was a first draft script title, and The Deadly Three.
Too Dumb to Live: During the production of Enter the Dragon, a would-be burglar to broke into a house and scared two children, Brandon and Shannon... not a good idea when they turn out to be the children of Bruce Lee! Not surprisingly, after one kick from Bruce, he got sent to the hospital for his idiocy.