Continuity mistake: When Braden is confronted by Cho's mother, she throws a blade at him, which he catches and throws back, sticking it in her shoulder. She uses a blowgun and there are two shots of her with the blade in her shoulder and blood on her clothes from the wound. However, when she misses there is a shot of her using a smoke ball where there is nothing in her shoulder, nor is there any blood on her clothes.
Continuity mistake: In the scene when Cho & Dave Hatcher confront the thugs in the park, the black thug is on the right, at the back, holding a radio. He says, "Oh look, here come the policemen. I wonder what they want with us this time?" In the next shot, the radio is on the park bench, in front of his knees.
Continuity mistake: The throwing stars which Braden uses to kill the one-eyed informant change from the time he throws them to the time they hit the guy. When Caifano picks up the body of the one-eyed informant, his right eye is bulging out. But after he says, "What the s**t is this?" his eye is back to normal formation.
Factual error: Star shuriken, despite common misconception, are not inherently deadly weapons. They were mostly used for distraction, since their lack of a single weighted point makes their attack rather inefficient (although the weapon could be coated with poison). Although it is possible to hit an eye, it is very difficult to hit such a small target or scoring a sufficiently deep wound to penetrate to the brain with a star shuriken.
Continuity mistake: Just before Cho kills Braden in the final fight, they use ninja-to (swords), but then suddenly the scene jumps to the swords lying on the ground and Braden using a dagger, which Cho drives into its wielder's belly.
Continuity mistake: The Masked Ninja (Braden) carries a lot of weapons which keep appearing and disappearing whilst he inflitrates Chifano's building; his spear-stick and a throwing axe (both relatively big - and therefore visible - weapons), for example, are both there whenever he needs them.
Deliberate mistake: When Braden confronts Cho on the rooftop, he uses dummies of himself to throw his opponent off-balance. But how could he have brought the bulky dummies onto the roof without being in the first place, or without proper preparation?
Plot hole: To murder Chifano's informant, Braden uses a throwing star. But there is one thing which makes this scene illogical: Braden is evidently not in his civilian suit, but in his ninja costume (the ninja suit's armsleeve is definetly on his arm). But since Chifano and the informant are looking in the same direction when the throwing star hits, and since a ninja costume would make Braden stick out like a sore thumb, it is VERY impropable that he'd escape the scene just like that.
Continuity mistake: When Braden sets out to kill Caifano's brother, he wears a business suit and carries a small bag as he enters the restrooms. But when he confronts his victim, he carries a ninja-to (ninja sword) in his sash. The sword is definetly too long to fit in the bag or under the suit, and I've never heard of dismantable combat swords.