Revealing mistake: Jareth sends a crystal ball to turn into the cleaners in the Oubliette. Right after the cleaners appear, the camera turns to Hoggle and Sarah, where Hoggle says, "Oh no, the Cleaners." Soon after, the two of them start to run. As they start to turn, look above at the ceiling. A light turns on to show them the way out.
Revealing mistake: Back in her room Sarah puts things away in her vanity drawer, including her music box. The diameter of the music box is greater than the height of the sides of the drawer, which would prevent the drawer from closing properly. On the white front of the vanity table above that drawer, the top lip is cut away to allow for the important shot of Sarah closing the drawer. (00:34:40)
Continuity mistake: When Sarah walks into the darkened bedroom, in the shots facing the double back doors the hanging light fixture over the crib, the mobile, and picture beside it are all visible. When Jareth appears, in the first shot facing him, the mobile hangs lower (note the archway), the picture is closer to the floral trim around the archway; and solely for Jareth's dramatic entrance, the light fixture is gone - though it should easily be visible in this shot, and the crib is now at an angle. (00:10:25 - 00:11:55)
Continuity mistake: When the Goblins are spooking Sarah in the dark bedroom, she spins round as a few pop out at the same time (near the vanity table, from the dresser drawer...), and one lifts the lid of a brown case atop the tall dresser. However, in the previous shots of the well lit room and when she first entered the dark bedroom, that case was gone - replaced with flowers. (00:08:35 - 00:11:35)
Continuity mistake: In the junkyard, after Ludo pulls Sarah out of the garbage room, Sir Didymus says "M'lady look, we're almost there...." and then there is a shot of the gates to the Goblin City. The junk which sits around the gates to the Goblin City is piled rather low. However when Sarah, Ludo and Sir Didymus arrive at the gates, the junk to the right hand side of the gates is now piled up much, much higher. (01:11:30)
Continuity mistake: When Sarah is hanging on the branch over the bog, Ludo calls a rock and the rock rolls into the bog, and is pretty round, with no large flat areas on it. However when it's floating in the bog, Sarah jumps onto it and the rock now has a very large flat area. (00:58:45)
Continuity mistake: As Sir Didymus bangs the large grey brick holding the bridge up and says "Have no fear sweet maiden...", the large brick then suddenly falls. Between shots the amount of green fungus and moss covering the grey brick increases. (00:58:10)
Continuity mistake: As Hoggle and Sarah fall out the end of the chute that leads to the Bog of Eternal Stench, look closer and you can see that Sarah falls through the end of the chute twice. (00:52:45)
Continuity mistake: Sarah is rescued from her fake house and head towards the gates to the Goblin City. Hoggle is seen poking his head out in the wide shot and then a close-up. The things around Hoggle change in the two shots. (01:14:25)
Revealing mistake: During the 'Dance Magic Dance'-sequence in Jareth's throne room, David Bowie throws up a baby dummy (it's near the end of the song). (00:26:00)
Continuity mistake: Ludo holds Sir Didymus up by his staff and promptly drops him on the ground. He gets up, whacks Ludo in the knee with his staff and then his plastic staff bends and folds over as it hits the knee. Yet in the following shots his staff is creaseless and straight again. (00:58:10)
Continuity mistake: After Sarah runs up the stairs and shouts, "I can't do anything right, can I?" in the next two close-ups of her stepmother, the foyer table stands on an area rug with multi floral at the edge, inner red floral and a center floral medallion. As the camera pans out in the next shot, the table stands on the medallion, whereas in the previous close-ups it stood farther over, on the red. (00:05:35)
Continuity mistake: The twin doors in the bedroom fly open, and as a result the curtains are opened and pulled behind each of the doors as the owl flies through. However in the close-up of the owl attacking Sarah the curtains are visible and they are now blowing in front of the open doorway. Then as Jareth's shadow is seen on the rug, it's clear that the curtains are pulled apart by their shadow, which is also the case in the next shot of Jareth standing in the doorway with the curtains indeed pulled behind the doors. (00:11:45)
Revealing mistake: After climbing up the ladder, Hoggle stands up in the large pot, then Sarah climbs out in the foreground and Hoggle is seen raising his body, to climb out of the pot too. However as Sarah lifts her leg out of the pot, Hoggle is seen lowering his body back into the pot. In the next shot he is beside the pot as if he just climbed out. (00:38:00)
Audio problem: Having reached her house after running home in the rain, Sarah's stepmother stands on the porch and we hear her say, "Oh, really," but her mouth does not move at all. (00:04:45)
Continuity mistake: When Sarah first meets the Goblin King, she has on Camel colored semi-formal flat shoes, but when she starts the labyrinth, her shoes have changed to brown suede loafers. She didn't change her shoes beforehand.
Revealing mistake: Numerous times you can see the 'metal' robot's metal armour and the spikes on the armour wobble like rubber. This is because the whole robot's armour is made of polyurethane foam. (01:13:30 - 01:15:00)
Visible crew/equipment: When the boulders start to roll into Goblin City, just after someone yells, "Good Grief" and just as the guards start to gather together, on the left of the screen a bug is seen going down a wall, then it's seen going up the wall, and the wire is visible. (01:24:30)
Visible crew/equipment: After just entering the labyrinth Sarah and Hoggle are talking. Hoggle says to Sarah "You know your problem? You take too many things for granted." As he says this, behind him you can see the blank, grey stage floor where they forgot to put the rusty gold colored set floor down, which matches the rest of the labyrinth floor. It isn't visible in any of the following or previous shots. (00:17:00)
Continuity mistake: When Sarah shouts, "Quick, this way!" and then Sir Didymus shouts, "No, not that way!" the hanging sign with the hammer hangs crookedly by only one chain. However, two shots later when Sir Didymus shouts, "You're going the wrong way!" the sign hangs properly from two chains. Then later, when the three Samurai Goblins jump in front of Sarah and the rest, the sign's chain is broken once again. (01:20:00 - 01:25:40)
Answer: The necklace is a symbol of Jareth's power throughout the story. All the time that Sarah is in the Labyrinth, Jareth has more power than her, because she doesn't really know what she's doing, and isn't taking one particular path, just getting lucky at the right times. At the end, as we all know, Sarah triumphs, and Jareth's necklace changes to admit his defeat.