Revealing mistake: At the end of the film, in the extreme close-up shot of the Dual Flintlock pistol Ronin having his forehead hacked by Itto's sword you can see his hair is a wig. (01:20:27)
Revealing mistake: During the final fight sequence between Itto and the Ronin there is a moment when Itto corners one of the men against a small wooden building and then decapitates him. His severed head falls to the left and his body to the right, however if you pay close attention to the body you can see his head is still attached. The severed head was thrown in from offscreen. (01:18:47)
Revealing mistake: At the hot spring village, when the Ronin are discussing Itto, there is a close-up shot of one of the men's face (when he says "He may be skilled, but he's with his kid so he can't do anything") and you can see his bushy eyebrows are fake as well as the beginning of his hair cap. (00:54:50)
Revealing mistake: After the attack on the village by the three assassins, Itto places his son in bed next to his dead wife Azami, and in the close-up shot of them you can see Azami swallowing. (00:17:26)
Revealing mistake: When Itto puts the cover on the baby carriage it's obvious that the sudden downpour of rain is just a sprinkler placed in front of the camera. Pay attention to the cover, Itto's clothing and the puddle behind the carriage, they remain completely dry/untouched. (00:11:00)
