Continuity mistake: Kevin sits down with a meal before the Wet Bandits arrive at the house consisting of macaroni and cheese on a plate. When Harry eventually makes it to the dining room, he is pelted with feathers. Look at the table to the left. A three part microwave meal still in its white plastic container now sits on the plate.
Continuity mistake: When Henry has just shown De Niro the guns and he returns to his car, you see him light up a cigarette. When the shot changes the cigarette has vanished. (01:54:45)
Visible crew/equipment: When Splinter throws Shredder over the wall, Splinter's puppeteer is visible. (Full screen only).
Continuity mistake: When Tracy is tied up in the basement, the rope around his body changes styles between shots.
Continuity mistake: When Kim is watching Edward cut the roses, in closeups she's quite close to the curtain, and it's hanging straight down. In the wide shot she's slightly further away, and the curtain is angled outwards because she's holding it back with her hand.
Visible crew/equipment: Near the beginning of the film when the police car explodes and flips over, you can blatantly see stunt wires used to aid in flipping the car. (00:02:45)
Visible crew/equipment: When a carload of bad guys drives past the front of Seagal's sister's house and riddles the front of the house with machine-gun fire, Seagal quickly slams the front door shut, and you can very clearly see all the stunt charges attached to the door.
Continuity mistake: When McLeach is using Cody to fish for crocodiles, the hook fastened to the rope around Cody's waist can be seen facing different directions in various shots. (01:06:45 - 01:09:35)
Continuity mistake: When Bob gives Nikita her birthday cake, the positioning of the candles in the cake change between shots. (00:31:55)
Visible crew/equipment: When Robocop visits Cain's hideout and sends his car in as a decoy, after he returns to the car, watch the driving shot closely. A wire has magically strung itself across the entrance and attached itself to the back of the car - it wasn't visible from an earlier shot. As the car drives forward it stretches the horizontal wire, and just as a tiny amount of pressure is exerted, the car explodes. Yeah, it's technically a mistake, but I think it's more worth checking out just to see how those tricky effects are achieved.
Visible crew/equipment: When Darkman swings on the wire to save Julie, you can see a large wire coming out of his shirt to support his weight, and you can make out several large wires holding Julie in the shot of her being grabbed.
Deliberate mistake: When Steven Seagal and Kelly LeBrock are in the jeep, being chased through some fields by the cops, some of the shots of the jeep are flipped. Note the bullet holes on the windshield switch sides, as does the driver/steering wheel, the windshield wipers and the front license plate. As an aside, also note the numbers/letters on the license plate that have been altered via CG in the flipped shots.
Revealing mistake: Just before Eleanor's car hits Phoebe, Phoebe's face is visible, and you can see that it's a stunt double, not Pamela Reed.
Continuity mistake: Frenger is wearing a gold-colored watch with a flexible band when he follows the thief's accomplice into the bathroom and beats him up. In the next scene, where Frenger purchases an Uzi squirt gun, Frenger is now wearing a watch with a black leather band. He did not steal the watch from the guy in the bathroom. (00:15:02)