Continuity mistake: When Kawada takes the picture with Keiko on it out of his wallet, you can see the picture from behind, because the light is on it. Then, when it is handed to Noriko, the picture is a completely different one. (00:54:20)
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. (01:03:30)
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.
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 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.] (00:13:35)
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: After Utsumi dies, her right leg is bent upwards and falls down onto her left leg. When Shuya finds her dead, both of her legs are straight.
Continuity mistake: When Shuya finds Utsumi dead, the proximity of her head to the girl behind her changes between shots, as does the position of her tie and gun beside her.
Continuity mistake: There is a scene in the movie when one female student ambushes another female student in her shack and the two girls fight. Initially the girl who ambushes is holding a Browning Hi Power pistol however when she drops it on the floor in the struggle it suddenly becomes a 1911 for the rest of the movie. (00:41:39 - 00:43:10)
Chosen answer: Specific aspects of direction may be from Reservoir Dogs, but the scene itself plays out almost exactly the same as in the book.