Jackie Chan doubled for Chikara Hashimoto for the scene where Chen kicks him out of the window. He took the kick and flew several feet. Bruce Lee immediately checked to see if he was okay. Chan played a guard Lee kills in Enter the Dragon (1973).
Bruce Lee openly admitted that in real-life, nunchaku versus the katana was actually an uneven match and should be avoided.
According to the book "I am Jackie Chan: My life in Action", Chan observed an argument on the set between Lee and director Lo Wei. When it looked like the fight would get physical, Lo hid behind his wife, Liu Liang-Hua. She was eventually able to calm Lee down.