Continuity mistake: When Captain Bollin is questioning Shaft in his office, his hand position between shots is not always consistent. Best example when he asks Shaft about Mascola: he is leaning with his left hand on the top of the file cabinet, but he's shown rubbing his hands together in the following shot. (00:29:40)
Revealing mistake: During the iconic dojo brawl scene, Bruce Lee at one point picks up two men and whirls them around. It's obvious in the wide shot that they are just dummies.