Continuity mistake: During the fight between A no 1,and Shack. Shack is cut with the ax, the ax head is coated with "blood," as A no 1 is setting up for another swing you can see the ax head behind his head, it is still "bloody," but as he starts the swing, the ax head is shiny and clean, and then it's bloody again.
Continuity mistake: When Shack and A no 1 fight in the train, almost at the end of the film, Shack tries to strangle A no 1 with a chain. A no 1 puts his left hand on Shack's chin with straight and separated fingers. In the next shot the hand of A no 1 is grasping the mouth of Shack with his hand in fist and tight fingers. This repeats twice between shots. (01:53:00)