Continuity mistake: When the "stoned" couple makes popcorn, it is shown being poured from a pot on the stove into a bowl, cooked properly. A short time later when Chris and her boyfriend are searching the house they come upon the pot of popcorn on the stove burning, and they empty it again.
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)
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 Harold is at the toilet you can see a shelf behind him with a fire extinguisher and a piece of cloth on it. Also the shelf is by his waist level. A moment later the extinguisher has changed, the piece of cloth is gone, the shelf is by his shoulder level and a clock has suddenly appeared on the wall. It is obvious this is a change of stage scenery. (00:13:15)
Continuity mistake: When Vera is sitting by the dock, Shelly grabs her foot from underwater. In one shot, her shoe clearly comes off, then moments later is back on perfectly. (00:53:40)
Continuity mistake: When the kids stop for the police cars who rush by we get to look out the back window of the car. You can see a car and a road sign there. These two wasn't there when they pulled over. (00:19:20)
Continuity mistake: Jason's left eye is much lower on his face than his right eye, but it sits in a normal position behind the hockey mask.
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 Chris is being choked by Jason in the van, the window starts off all the way down and then Chris turns the handle one full circle. In the next shot it is rolled up all the way. (01:17:05)
Continuity mistake: Vera drops Shelly's wallet in the lake. She stands up and tries to reach it. Seconds later it has floated a ways from the dock but remains in the same spot until Vera goes in the water and picks it up.
Continuity mistake: When Vera is picked up by Chris, she brings no luggage with her yet throughout the movie she changes clothes and shoes.
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: When Jason moves to spear Loco with the pitchfork, the prongs are curved down. But when it goes through him, the prongs are suddenly pointing upward. (00:40:25)
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: Harold puts the fishfood bottle down on the counter with no lid on it. However when he's eating the doughnut you can see the fishfood bottle is now on the till, with it's lid on. (00:10:55 - 00:11:40)
Continuity mistake: When Chris jumps down on Jason you can see a lamp shade lying on its side as they land on the floor. When it cuts it is suddenly lying upside down. (01:19:40)
Continuity mistake: When Ali punches the car windshield, it is clear that the whole pane of glass is smashed out, but in the next shot the pattern of the missing glass is completely different. (00:32:15)
Continuity mistake: Between shots, as Harold spit's the fish food out, the position of the figurine fisherman's wooden rod changes. (00:10:50)
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 Debbie is killed in the hammock, the knife goes through her breast. Later, when Chris pulls the knife from her, the knife is suddenly in her neck. (01:02:25 - 01:13:55)
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