Many, as Bruce Lee's role in this film was composed entirely of archival footage. Most noticeable is when his character visits the Abbot, who alternates between a man with a grey beard and red costume to a man with a white beard and a yellow costume.
Bobby Lo somersaults forward over Chin Ku in mid-air, however he's finishes it backwards in the next take.
The wire to pull the monk in mid-air (after being thrown by Bobby Lo) is a little too late, he ends up being pulled along the ground instead.
When Bobby-Lo is fighting wildman, one of the supposedly dead guards in the background raises his head and looks around.
When Lewis delivers the final kick to the face of the second of the Wu/Yen brothers, a wire harness for the stuntman can clearly be seen sticking out from the arms of his vest.