Incorrectly regarded as goofs: The armor the samurai wear is from the mid- to late-Sengoku Jidai era in Japan, over 250 years before the Meiji Jidai era the film takes place in. However, this was deliberate. Costume creators were aware that at the time the movie takes place, no armor would have been worn. They chose to have them in armor to show that the band of samurai wanted to go back to old values and rejected modernity.
Factual errors: General Omura Masujiro who developed the Western-style army during the Meiji restoration was killed in 1869 by a conservative samurai, several years before the movie takes place.
Continuity: Nobutada's blood around his mouth disappears and then reappears while talking to his father before his death.
Continuity: When Katsumoto is in the courtyard discussing poetry and perfect blossoms, he has a cut on his forehead from the ninja attack. He announces that they will be departing the next morning, but when we see him the next morning, the cut has completely healed.
Continuity: When the son is killed, a soldier turns the corner, and rips the wall with the butt of his gun. In the next shot, the wall is not ripped.
Continuity: When Nathan is illustrating the scalping procedure to Simon Graham, in one shot he is seen pressing the knife against Simon's throat. In the very next shot the knife has moved away from his throat.
Continuity: When Taka is washing her hair and talks with Nathan, her hair is alternately in/out of her kimono between shots.
Factual errors: No one, especially a foreigner, would have been allowed in the Emperor's presence bearing weapons, yet this happens on three occasions.
Continuity: During the discussion about the scalping, Zebulon Gant's hand jumps around in the background between holding the chair and holding up his glass so that he can sip from it.
Continuity: When Nathan walks into Taka's house after his first round about town since his capture, Taka cleans up after him because he has walked in with muddy shoes. The shot before this showing him walking in the door clearly shows clean shoes.
Factual errors: When the samurai are entering the town, a photographer is seen with a large format camera. On the matte screen, the scene is depicted in sepia-tinted black and white. It should be in full color, as in every camera or camera obscura.
Continuity: During the final charge of the Samurai, Algren has his sword in a "stabbing" grip, ready to throw it. A few shots later, he has the sword in its regular position, flipping it to the throwing position again.
Anachronisms: The Meiji Emperor would not have been called by that name until after his death. Meiji was his "nengo", or reign-name, and that name for Japanese emperors is only used after their death; e.g. the Emperor Hirohito is now known as the Showa Emperor, Meiji's name was Mutsuhito, and he was referred to as Emperor Mutsuhito during his lifetime.
Continuity: After the final charge of the samurai there are several moments where the weather changes from sunny in wide shots to raining in close-ups.
Revealing mistakes: Obvious stunt double when Nathan falls off the horse in the final battle.
Continuity: When Katsumoto and Algren are riding to Tokyo, Algren is seen turning around his horse and starting to ride off. In the next shot, he is not moving and beings to ride off again.
Revealing mistakes: During the final battle when the samurai are lighting bales of hay on fire to cover their retreat, the fire spreads to the last two visible bales before the rider on horseback reaches them with his torch.
Errors in geography: There are no wild palm trees in Japan except in a few southern areas.
Revealing mistakes: Obvious rubber gun (top left of the screen) in the slow motion sequence during the final battle.
Continuity: When the ninjas attack the samurai village, Algren is being pinned down by a ninja who is trying to force his head onto a blade. In the next shot, Algren throws off the ninja, but in the subsequent close-up, the ninja is back on his back and he throws him off again.
Plot holes: Algren finds the Hakama, Dogi, and Obi in his room, and then walks out of the room fully dressed. Wearing the Hakama and Dogi requires the tying of no fewer than four very complicated and precise knots. Yet, when we see Algren emerge from the room, he looks perfect - there is no way he would know how to put on Japanese clothing.
Audio/visual unsynchronized: When Algren and Katsumoto are shown in slow motion, during the horseback charge, Algren draws his sword and we hear the sound of the sword ringing as it is drawn. The Saya (scabbard) of the Katana is typically made of wood, and though they sometimes had fittings made of metal around the Koiguchi (mouth of the scabbard) these were usually ornate, and there clearly are none on the sword that Algren has.
Audio/visual unsynchronized: The technique of drawing a katana and the material of scabbard (saya, made of wood) doesn't generate such sound as it can be heard in the movie.
Continuity: When the ninja invade Katsumoto's village, a ninja is shown quietly killing a samurai sentry by snapping his neck. Later, just before the final battle, the same samurai is ready for battle and staring the enemy army down.
Revealing mistakes: During the ninja attack in the house when Nathan and Katsumoto are fighting inside the house together. One of the first ninjas on the right hand of the screen that was injured or killed during the attack is seen rolling out of the way for the second group of ninjas to jump through the wall and attack.
Continuity: When Algren is rescuing Katsumoto from his "home in Tokyo", one of the soldiers from the first group of soldiers that get a chance to fire has an arrow protruding from his back, with no ill effect, before the first arrows are loosed. It is clearly visible through the smoke from the guns.
Continuity: During the wooden sword fight in the rain, (after Nathan spars with one of the young boys), he gets a bloody nose from a blow to the face. In the very next shot, the blood is gone.
Continuity: During the wooden sword fight in the rain, (after Nathan spars with one of the young boys), in the first sequence, the sword is struck from his hand and flies away. As he stands up from the blow without moving to retrieve it, he has it in his hand again.
Factual errors: At the beginning of the film, the narrator talks of a "sword" which was dipped into the sea and the four islands of Japan were formed. This is factually incorrect; it was actually a jewelled spear, called Ame no nuhoko and is detailed in the Kojiki, the book of the Shinto faith.
Factual errors: Japan *did* seek military advisors in the latter half of the 1800s to form a modern Army. The only problem with this is that they didn't consult the Americans to assist them. The most successful army at that point was the Prussian (not yet German) Army, whom they recruited for training purposes... as well as British naval attachés to assist in the creation of a modern fleet (which thoroughly embarrassed the Russians at the Battle of Tsushima in 1905 and established Japan as a fledgling world naval power).
Continuity: When Nathan is walking through town and is approached by the Shogun's men, there is a close-up of him putting his hands at his sides. The very next shot has him lowering his hands again.
Factual errors: The first battle is in a forest which contains tall tree ferns. There are no tree ferns in Japan, only small ground cover type ferns.
Revealing mistakes: In the final battle sequence, one soldier takes an arrow directly in the face. But the actor's hand is already held up to his face, palm inward, before the arrow arrives.
Continuity: Tom's thumb has a bruise on it when held captive, in the fall. In the spring, the bruise is still there. Most bruises disappear after a month.
Continuity: During the ninja fight when Katsumoto is at a stand off with two ninjas, one ninja has a sword and the other is holding two sai. In a close-up of the ninjas, both are holding swords, and then in the next shot of both ninjas, they have their original weapons again.
Anachronisms: There is a modern telephone pole in the village.
Continuity: When Nathan hands the wooden sword back to the boy in one shot, it is between his middle and ring fingers. In the next shot, he is holding it normally. He switches back and forth twice more.
Revealing mistakes: When Katsumoto, Algren and the rest of the Samurai are charging on horses towards Colonel Bagley and the infantry in the final battle. Katsumoto is shown with a bullet hole in his shoulder armor, moments later he is shot in the exact spot. The bullet hole was there before he was shot.
Incorrectly regarded as goofs: At the final battle Algren tells Katsomoto about the battle at Thermopylae. He tells him that 300 brave Greeks held of an army of 1 million Persians. This is in fact wrong. There were 300 Spartans (It is believed that they had allies). But the Persians invaders were only close to 150 000 men. Of course, stories from ancient times describe the brave Sparta's as heroes who stood up against 1 million Persians, and at the time of the movie it might still have been thought so. Anybody could have made this misconception, but the reason behind the story would still be the same. A small force severally outnumbered faces a larger force without fear for what they believe is right.
Factual errors: Japanese are constantly bowing to each other as part of normal interpersonal relations. It is part of their character. In the movie, there is hardly any bowing. The minimal bowing that is shown in ceremonies, etc., is so perfunctory as to be disrespectful.
Miscellaneous: After Katsumoto and Algren meet with Colonel Bagley and Omura before the final battle sequence, Algren rides back into the Samurai front lines, when he dismounts his horse you can see the horse kickback and hit one of the Samurai who then stumbles backwards unsure of what just happened.
Continuity: In the beginning, when Algren is doing the performance for the Winchester company, he fires a bullet at a bell. Before shooting the bell, he blows three whistles off of a calliope in the back of the room. When the camera does a close-up after he shoots the bell, only two of the whistles are missing.
Revealing mistakes: The shot where they are disembarking the ship in Japan you can see the green screen spill on the side of the ship and a hole through the ship revealing the CG water behind.
Continuity: In the middle of the movie, when Algren is experimenting in his new robe, the boy is seen watching him and begins to bow after being noticed by Algren. In the next shot, the boy's head is suddenly upright again.
Continuity: During moments of the samurai's last cavalry charge into the infantry line, Colonel Bagley can be seen without injury after his supposed earlier impalement with the sword thrown by Algren.
Errors made by characters (possibly deliberate errors by the filmmakers): When Graham, Algren and Gant are examining the Japanese texts, Grant remarks that the Samurai are still wearing Armour. Graham responds to this remark by claiming that the Japanese were the most advanced people in the world while at the same time the Irish were still in loincloths, clearly an insult aimed at Gant. Billy Connolly is however Scottish as is his accent, not Irish.
Incorrectly regarded as goofs: The seppuku ritual in the film is correct for a battlefield. A person committing seppuku on a battlefield would in fact have his head fully decapitated; later, more ceremonial rituals, involved leaving the head still partially attached. However, since General Hasegawa was commiting suicide on a battlefield, his second (Katsumoto) would sever the head completely.