Revealing mistake: At the beginning of the film O-Yuki is fighting the men in the forest and kills them one by one. When she kills the last one there is a close-up shot of her dagger entering his rib area and blood sprays out. However, if you pay close attention you can see the blood sprays out of his sleeve (presumably there is a device in there), not his torso. (00:01:18)
Revealing mistake: During the flashback sequence when Gunbei's double is decapitated, his severed head hits the floor but you can see that the actor's head is still inside his clothing. His top has been pulled over his head to make it look like his head has been cut off. It's even more obvious in the wider shot right after. (00:27:42)
Revealing mistake: After defeating Gunbei in a duel, Itto is ambushed inside a temple. During the fight a number of the assassins have their arms cut off, however if you pay close attention you can see that they have just tucked their arms behind their backs. The shape is very clear in the clothing. This is most obvious during the shot of the two assassins dying on their knees and moaning, just before Itto executes them. (00:36:15)
Revealing mistake: When O-Yuki is having a flashback to the duel she had with her trainer, at one point he "magically" sets his sword on fire. However, if you watch the scene carefully you can see a cord that runs from the sword into his robes, probably some kind of fuel line. You can see it twice: once in a wide shot showing the trainer and O-Yuki when he laughs and slowly raises the sword and a second time when he blocks O-Yuki's attack and punches her in the stomach. (00:45:58)
Revealing mistake: Throughout the film, whenever there is a close-up of the face of a male character, you can often see the stitching where their hairpiece is sewn into their real hair.
