Continuity mistake: When Debbie is killed in the hammock, in all shots of her, the quilt covering the hammock net has patterns sown on it, such as flowers. However, in the closeup of Debbie as the knife comes through her chest, the quilt covering the hammock is the same one as before, however you can now see it is suddenly the other side of the quilt. (01:02:25)
Continuity mistake: When Chris knocks Jason out with the shovel, the position of unconscious Jason's legs changes between shots. (01:20:30)
Continuity mistake: When Chris and Rick get stuck in the woods, Rick puts a coat on Chris. In a wide shot Chris pulls the sleeves of the coat up and then starts adjusting the shoulders of the coat. It cuts to a closeup and she is now rolling the sleeve up again, and then adjusts the shoulders again too. (00:42:35)
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 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: Jason approaches Loco with a pitchfork with five prongs, but the pitchfork that enters Loco's stomach has only four prongs. (00:40:20)
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 Chris runs into the bedroom away from Jason, there is a long decorative picture hanging to the left of the window, and between shots a long piece of brown string, hanging down the painting, alternatively appears/disappears. (01:14:30)
Continuity mistake: When Harold feeds the fish, in wideshots there is a note next to the fishbowl which reads "Say Hi to..." However in the closeups of the fishbowl, the note has gone, and should be visible. (00:10:20)
Continuity mistake: Right before Chris stops the van to avoid hitting Abel you can see that none of the others are in the back of the van. (00:20:25)
Continuity mistake: When Jason is chasing Chris, Chris runs into a bedroom and onto a bed, and then grabs a chair to smash a window, and the chair flies out the window. However, when Chris falls out the window we see the chair again, however the chair is a totally different chair, as the spindles on the legs of the chair have totally changed, and the back to the chair is different. (01:14:35)
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)
Continuity mistake: When Chris first enters the cabin and talks with Rick, and also in later scenes throughout the movie, the hat hanging on the pegboard beside the cabin door changes position a few times between shots. (00:22:20)
Continuity mistake: When Harold is on the toilet, the toilet roll sits on the centre of the shelf behind him. Moments later when he looking around, it is right by the edge of the shelf. (00:13:25)
Continuity mistake: When Shelly screeches out onto the road, after the windows on the car are smashes by Ali, you can see a large 'Olympia' lorry parked perfectly straight, outside a garage. Then between shots when Shelly goes speeding towards the gang's motorbikes, the lorry is suddenly parked at an angle, now sticking right out into the road. (00:32:20)
Continuity mistake: After getting out of the shower, Debbie still has her silver necklace on. She leaves the bathroom and the necklace has disappeared. (01:01:15)
Continuity mistake: When Andy is cut in half by Jason, blood spurts everywhere. However when Debbie gets out of the shower and she walks through the same area and there is no blood anywhere for her to notice. Jason didn't have enough time to clean up the area. (01:00:15)
Continuity mistake: When Chris spots the axe in the stable at the end of the film, it goes from laying on the hay, to on a metal object between shots. (01:22:55)
Continuity mistake: When Chris comes out from the green door waving a knife at Jason, the green door closes all the way behind her. It cuts to Jason and then back to to Chris, and behind her in the background the green door is now wide open. (01:14:10)
Continuity mistake: When Harold finds the rabbit in his store, it is in a crate of vegetables. Between shots, the vegetables which are in all of the crates change; for example some of the broccoli stems turn into lettuces in the next shot. (00:10:55)
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