Continuity mistake: During the opening fight scene, the evil ninja hangs onto the left side of a helicopter and uses his left foot to throw a shuriken at the pilot. The shuriken somehow hits the pilot on the right side of his face rather than the left. (00:09:15)
Continuity mistake: When Billy inspects Christie's sword, he's holding it hilt up in the wide shot. In the close-up, he's holding it hilt down. (00:30:30)
Continuity mistake: In the fight scene between Ninja Christie and the cop playing billiards, she stops him from getting his gun then she kicks him into the wall. In the next shot, she somehow is again at the opposite end of the billiards table. (00:38:30)
Continuity mistake: Hanjuro slashes a woman on the arm during the opening fight scene. In the close-up, she somehow got a wound on her shoulder that wasn't there before. (00:04:55)
Continuity mistake: This happens in the scene where the possessed Christie seduces then kills the cop in the hot tub. When he pulls away from her embrace after he realises that she's poisoned him, he's holding onto her with both hands. In the next shot he's holding her with just one hand. (00:44:10)
Continuity mistake: When Ninja Christie fights a cop who was playing billiards, he fights her back with a pool cue. She jumps on the billiards table and chops his pool cue to pieces till he drops it. In the next shot, he is again holding the pool cue. (00:38:15)
Continuity mistake: When Ninja Christie fights a cop in a graveyard, the cop smashes a headstone with his baton. The damage on the headstone changes between shots. (01:06:25)
Continuity mistake: Ninja Christie kills the cop playing billiards by slashing his face then throwing him onto a wall. The next shot shows that he instead flies out of the window. (00:38:50)
Continuity mistake: During the golf course opening scene, a motorcycle cop gets kicked to the ground by the ninja swinging from a grappling hook. In the next shot, the cop somehow falls into the water hazard along with his motorcycle.
Continuity mistake: When Yamada leaves the temple, the shadows on the matte painting long shot don't match at all the shadows on the closer angle of the stairs. (01:22:30)
Continuity mistake: When Christine looks at Yamada before falling unconscious, the sword scabbard is right next to her at the bottom of the frame, but it's at greater distance in the previous shot and rest of the movie (like when her boyfriend wakes her up), except when the black ninja rises, when it's gone. (01:19:15)
Continuity mistake: When Christie draws her sword and brings it down over her stalkerish boyfriend (but alas, doesn't kill him), he clings to the bedframe with both hands, but has just one arm raised in the second shot. You'd think the arm is down on the ground for good as shown in the room view too, but in the very last shot he's again gripping the frame. (01:15:25)
Continuity mistake: When the good ninja KOs the cops in the car, the hat on top of the last one is tipped in an entirely different way in close-up and wider angle. (01:13:10)
Continuity mistake: During the close-up of Sho Kosugi looking languidly at Christie's boyfriend when the cops are taking him away, look at the blonde moustached cop behind him. His face is in the shade, and then suddenly in direct sunlight at the cut. Same for his fist as he holds the gun in this second shot; direct sunlight on it, shadow during the next close-up on the ninja. (01:11:25)
Audio problem: In the cemetery, Christie fights a cop who attacks her with a baton that makes a super-exaggerated 'swoosh' sound; exaggeration aside, the last 'swhoosh' happens during a motion with no speed, so the sonic boom there is not just overkill, it's wrong. (01:06:40)
Continuity mistake: After one of his coworker smashed a gravestone with his baton, a second cop gets close enough to the ninja to grab his/her arm. The ninja punches him away with a blow from right to left, which is not in continuity with the previous shot. (01:06:35)
Revealing mistake: After the sequence where the cops eagerly arm themselves with batons (at the funeral of two dozen armed with guns), the ninja disposes of a single motorcyclist. As she knocks him off the bike, you can see on the path the dirt marks at the center of the asphalt from previous takes. (01:06:10)
Continuity mistake: When Christie's wardrobe tries to suck her in, the items that are being drawn in and therefore slide on he floor, change between shots with no logic. For instance, we see an empty metal vase, then the same vase with marbles, then just the marbles. (01:02:00)
Revealing mistake: Somehow, every ninja in this movie is really bad at being undetected. Sho Kosugi gets caught again by a guard after fighting with the ones outside the morgue, and disposes of him with a roundhouse kick. The stunt is comically bad, because you can see the guard literally throw himself at the wall headbutting it. (00:55:50)
Revealing mistake: At the climax of the exorcism scene, Christie begins spinning at great speed. That's an impressive supernatural feat already, but the real scary part is that to do, so she also transmorphs into a dummy. (00:52:40)
