Revealing mistake: When Shin begins chopping off Jay's head, in the close-up shot a line can be seen around the part of Jay's neck that hasn't been cut yet, revealing that it is a prop head. (01:35:05)
Revealing mistake: When Shin shoots Ami in the stomach, it is apparent that the blood spurt that emerges from her stomach is a poor CGI blood spurt. The blood shown is too bright to match the lighting and there is no stain or rip shown in her clothing. (02:17:45)