Revealing mistake: Many times throughout the movie, people are shot and they bleed, but their clothes don't have holes from where the bullets hit them. The most noticeable examples are when the teacher is shot at the end, and when the big gun fight between the girls breaks out in the lighthouse.
Continuity mistake: When Kiriyama beheads Oda with Samurai sword, he is alerted to the noise in cottage where Kawaka, Noriko, and Nanahara are hiding. Inside the cottage, the trio see Kiriyama's blood-stained hand smearing the window. Then, Kiriyama hurls Oda's head, grenade in mouth, through the window and into the cottage. Despite Kiriyama's hand being soaked with blood, Oda's head is clean and spotless.
xx:xx:xxAllister Cooper, 2011
Continuity mistake: After Kawada gets his bag, he realizes something and returns to the classroom. Tossing the bag back to the soldier who threw it at him, he points to a bag behind him on the cart and tells Kitano, 'That's my bag.' In the next shot, he is pointing to a bag in front of him.
Add timeAllister Cooper, 2011
Plot hole: After Nanahara and Noriko run away from Akamatsu at the school, Niida shows up from behind some bushes opposite the school and inadvertently kills Akamatsu with his crossbow. But Niida is Boy 16, which means he should still be in the school building (he's supposed to come out after Noriko, who's Girl 15). There's no way he has any time to get into those bushes.
Audio problem: When Chigusa attacks Niida after he shoots her with an arrow in the cheek accidentally, she stabs him in the back, they fall and roll to the floor, and then he tries to escape from her and begins ro run away, but she grabs him and screams "Bastard!!" However her mouth is completely shut.
Continuity mistake: When Yuka Nakagawa is poisoned, her face lands in the bowl of poisoned spaghetti. A little later as the girls begin shooting each other, her face is now out of the bowl, and on the table instead. There was no movement to suggest that her face fell out of the bowl, as it quite clearly happens between shots (just before the girl jumps ono the table.)
Continuity mistake: In the first shot of Yuka Nakagawa as she covers her mouth after being poisoned with KCN by Yuko Sakaki, there is no blood on her hand as she has only just started to react to it. But in the closeup shot immediately afterwards there is blood already seeping through her fingers.
Continuity mistake: When Shuya Nanahara is being chased by Kazuo Kiriyama, Shuya shoots at Kiriyama twice, hitting Kiriyama in the chest and causing him to be knocked back a little, as he is wearing the bulletproof vest. However, when Kiriyama has Shuya cornered, there is no trace of a bullet hole.
Continuity mistake: In the initiation scene, Kitano kills Fujiyoushi by throwing a knife at her head. The knife penetrates her skull almost in between her eyebrows. Yet when he pulls the knife out, it looks as if the knife actually struck her under the eye or on the cheek. [And although this may have been corrected in some versions, it still exists in some versions and can therefore still be mentioned as a valid mistake.]