(at around 59 mins) In the Iron Monkey's first fight with the witch, she cuts off his braid of hair. However, in some scenes after the fight, it's there again, and in some scenes, it isn't.
(at around 1h 4 mins) Just after Miss Orchid put the needles in the back of Dr. Yang to get the poison out of the Buddha's Palm, she lays him back in the chair, and then we see his back without the needles, and it never shows her taking them out.
When Master Fox is hit in the face by one of the real investigator's guards, his face already has red bruised makeup before he's hit.
(at around 28 mins) While making dinner, Miss Orchid tells Wong Kei-ying that she makes a very special chili. While her back is turned to continue cooking, her lips don't move but she is able to tell him how hot it is.
(at around 41 mins) When Dr Yang plays the monocord, we hear vibrato, but the fingers in his left hands are not moving.
(at around 1h 1 min) As the Iron Monkey is about to climb up the ladder after the fight with the Royal Minister, you can hear the sound effects of him climbing the ladder before he begins climbing it.
Support wires are visible during the final fight, especially when Dr Wong does a full split.