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: 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)
Continuity mistake: The priest is praying and unknowingly almost exorcises the evil ninja, he is holding his onusa (the stick thingy) with one hand or both hands, and when they both speak Japanese the grip of the left hand differs between angles. (00:50:00)
Continuity mistake: Once Christie is all tied up, the ceremony begins. Miyashima is holding a pipe that faces opposite ways between shots when he holds it with both hands. Still holding it with both hands he brings it to her lips, then in close-up suddenly he holds it with just one hand. (00:49:20)
Revealing mistake: During the movie, the ninja crushes with their bare hands a golf ball (in the opening fight) and a billiard ball (in the fight against Case). Both times the ball is replaced by a shell filled with talcum powder. It's especially conspicuous in the case of the cue ball, because the previous 'stunt' involved slicing one in half and the ball looked nothing like the one she 'pulverizes'. (00:04:00 - 00:38:35)
Continuity mistake: In the opening kick of the billiard fight, Christie's foot touches the Miller time lamp suspended over the pool table, which logically begins to undulate. In the next shot, the lamp is perfectly still and untouched. Similar mistake a minute later at the end of the scene; when she leaves using the window, the lamp is moving but almost comes to a complete halt, only to be back swinging wildly at the cut. (00:38:00 - 00:39:00)
Continuity mistake: The scene where Christie eventually succumbs to the arcade machine begins with her top bearing a huge sweatstain throughout the whole length, but ends with the stain considerably reduced (to be fair, there is no frame of reference to categorically exclude that laser beams emitted from bootleg cabinets possessed by evil ninja demons double as dryers, but we can assume it's not the case). (00:33:15 - 00:35:20)
Continuity mistake: Christie triggers Secord's odd tomato juice fetish, and they have sex. She wakes up and checks out the katana in the wardrobe. The sword floats shaking in different ways depending on the camera angle, and the lighting wildly differs as well. (00:29:00)
