Continuity mistake: When Meo and 16 are competing with weapons, 16 has a staff but when he bows to grand master he has 2 swords in his hand.
Plot hole: When the 3 ninjas' Grandpa is in hospital, he phones them and complains that no-one at the hospital speaks English. Not only is this a strange complaint to make about a hospital in Japan, but later in the film he is seen speaking in Japanese. He should therefore be able to easily communicate with people at the hospital.
Visible crew/equipment: Rocky is chatting up Mijo and the other two boys, Colt and Tum Tum, burst through the paper screen. In the next shot, very bright studio lights are reflected in both lenses of Rocky's spectacles.
