Revealing mistake: Throughout the movie, people getting shot almost always don't have the shot angles line up with how they appear. This is especially obvious in the end scene with Hit Girl shooting the gangsters: she might shoot someone at an angle from the side, but the shot appears to have come from directly behind the person.
Revealing mistake: In the sequence initially introducing Hit Girl and Big Daddy near the beginning of the film, where Big Daddy shoots Hit Girl in a training exercise, no bullet hole appears in her overcoat, despite her having to unzip it to remove the projectile from her bullet proof vest. In the wide angle shot, padding from the coat is see bursting into the air upon impact as she is knocked back to the ground. In subsequent shots, no bullet hole is ever visible in her coat either. (00:12:55 - 00:13:48)
Answer: Guy: "You'd rather die for some piece of shit that you don't even fucking know? Kick-Ass: "And three assholes, laying into one guy while everybody else watches, and you want to know what's wrong with me?! Yeah, I'd rather die, so bring it on!"