Continuity mistake: When the camera pans past the window, to the door, showing Chris walking up to the cabin, there is no painting hanging next to the door. When she gets in and talks with Rick, there is a long painting hanging to the right of the door. (00:22:25)
Continuity mistake: When Chris enters the cabin, Rick grabs her, and the cabin door swings to an angle so it's half shut. In the next shot of Rick it's open wide. (00:22:45)
Continuity mistake: When Chris pushes the crooked painting straight, there is a lamp in front of it. In the next shot the lamp is to the left of it. (00:23:15)
Continuity mistake: When Chris shows Debbie the hammock, between shots the way the net hangs and the position of the net changes. (00:24:55)
Continuity mistake: When Chris shows Debbie the hammock, she removes a board and lowers her arm. When it cuts her arm is back up on the board. (00:24:55)
Continuity mistake: When Rick is hoisting up the hay into the barn, and talking to Chris, he hoists up a block of hay with Chris standing on it. When Chris says "Were you talking to me?" she hangs to the left of the rope. In the next shot she hangs to the right. (00:26:25)
Continuity mistake: At the barn when Chris is being dragged up by Rick and Rick says, "You agree, I agree." you can see his hands gathered while holding the rope. When it cuts his right hands have moved further up the rope. (00:26:30)
Continuity mistake: When Nick walks into the room, after Chris discovers Shelley in the cupboard, he leaves the door wide open. When the others enter the door is half shut. (00:27:55)
Continuity mistake: When Shelley runs and stops Vera in the car, to ask if he can go with her to the store, the car is in sunlight. In the next closeup, as she drives off, it is in complete shade. (00:28:35)
Continuity mistake: When Shelly throws his wallet to Vera, he has a silver band around his left arm. Then when he says "Excuse me, but I believe that's my wallet", it has disappeared. (00:29:50)
Continuity mistake: When Fox takes the wallet in the store and talks with Vera, between consecutive shots her necklace changes position. (00:30:05)
Continuity mistake: When Fox says, "You mean, may I please have the wallet." to Vera, she is holding the wallet. In the next shot you can see the wallet is rotated. (00:30:30)
Continuity mistake: When Vera asks Fox, "May I please have the wallet?" you see Vera holding the wallet unfolded. When it cuts the wallet is folded with no time for Fox to fold it. (00:30:30)
Continuity mistake: When Shelly and Vera are walking out of the store, Vera stuffs Shelly's wallet into her beige pants. Later, while sitting on the dock, she pulls it out of her pink pants. She doesn't have a change of clothes with her. (00:31:05 - 00:56:40)
Continuity mistake: During the scene in the car outside the grocery store, the number and position of tyres on the metal tire rack standing near the beer lorry changes. (00:31:25)
Visible crew/equipment: After Vera says "uh-oh," as her and Shelley sit in the car outside the grocery store, the camera pans around to the side window. You can see a hooded cameraman reflected in the small triangular window, as the camera pans. (00:31:30)
Continuity mistake: When Shelly and Vera get into the car after their run-in with the biker gang, you can see the area around where the windshield wipers are attached to the bonnet is all perfectly painted. However after Shelly reverses into the motorbikes, it cuts to Shelly and now there are large areas of rust around the wipers. (00:31:30)
Visible crew/equipment: When Shelly and Vera are getting ready to leave the store we see Shelly start the car and you can see the microphone in the windshield of the car. (00:31:35)
Continuity mistake: When Ali pulls up his chain before he smashes the front shield of the car a piece of the chain is hanging down. When it cuts the chain is perfectly rolled up. Then later when he is about the break the side window it happens again. (00:31:55)
Revealing mistake: After Ali has smashed the front shield of the car it is obvious the window isn't made of real glass. It's made of plastic. (00:32:15)
Answer: Friday the 13th Part III in 3D is also available on Blu-ray as part of a set of all the films from 1980 to the reboot. I know because I own it. There are two pairs of 3D glasses included in the tin.
Alan Keddie