Revealing mistake: When Han's daughters/bodyguards are throwing daggers at the apples in the banquet room, one girl just blows the dagger out of her palm and catches the apple in mid air impressively. However a keen eye can see the wire attached to the dagger that pulls it from her hand (slow-mo is not necessary).
Visible crew/equipment: The head of a crewmember is visible during the mirror room fight. During the part where Lee is slowly moving across a mirror (just before he turns down the corridor and Han comes up behind and slashes his back), look down the corridor where Bruce is about to turn down and you should see it. Also after Han slashes his back Lee turns around and goes back down the corridor and you can see this crewmember again but more.
Continuity mistake: After Bruce has scared the radio controllers from their booth with the cobra we see him calmly resting his palm on his cheek. Cut to another shot of the radio guys splitting and his palm is more at his temple. The shot goes back to him and it's on his cheek again.
Factual error: During the flashback explaining what happened to Su Lin she has an ugly bruise on her face less than a minute after being hit. Bruises usually take at least a few hours to develop like that.
Revealing mistake: When Lee's sister is seen running from the men pursuing her, she falls down and you can see the stunt mat she falls on. It looks like the makers tried to cover it up with some dirt but if you look at the lower left corner you can see the green fabric of the mattress where they missed a spot.
Audio problem: You hear a clunking of metal when Hanh hits Williams, especially when Williams throws the side kick. Clunking of metal can only be heard when metals clash. Even when metal hits rock, a different sound is made. So when flesh or bone clashes with metal, this sound cannot be made.
Visible crew/equipment: Near the end of the movie, Bruce Lee knocks Han to the ground and then the shot changes to show a frontal view of Bruce. He then lands a kick to Han's head that sends Han flying across the room. As Bruce moves towards the camera you can see a pointy object on the left side of the screen that a crew member must be holding, because in the next shot there is no pointy black thing in Bruce Lee's path. (01:34:30)