Continuity mistake: When Hoggle jumps off the huge metallic robot, we see him land parallel to the foot of the robot as he lies on the ground. When Sarah runs to him, Hoggle's head is now right up against the foot, while he lies there. Yet in the next shot as Sarah asks if he's alright, still lying on the ground, he is not near the giant foot. (01:17:50)
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)
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)
Revealing mistake: In many shots throughout the film it is very obvious when it is a blue screen, plate and/or matte painting shot, by the area around the subjects and/or the subjects' appearance or disappearance onscreen. Some examples can be found with the Fireys and Sarah, during the Chilly Downs scene, and later, when Sarah breaks the glass with the chair, part of her face disappears when she stands with the glass behind her. (00:51:00)
Continuity mistake: When Sarah crosses the Bog of Eternal Stench, the bridge rails break, and then the bridge plank under her gives way and falls into the bog, while she clings to the tree limb. However, when Sir Didymus says, "It seemed solid enough," the left rail and the bridge plank are actually still intact. (01:00:25)
Continuity mistake: When Ludo calls the rocks in the Goblin city, there is then a wide shot of Sir Didymus standing by a house door, surrounded by soldiers. Between this wide shot, and the next closeup, the soldier's spears go from not being pointed at Didymus, to being pointed right close to him. The spears being pointed at him in the closeup also are different to the spears that belonged to the guards in front of him too (check the flags hanging at the end of the spears.) (01:20:35)
Continuity mistake: When Sarah sits down at her vanity table in her fake room, in a wide shot you can see her Labyrinth book laying on the table. The angle the book is laying at changes when Sarah picks it up in a closeup. (01:09:55)
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)
Continuity mistake: When Sarah is talking to Jareth about entering the labyrinth, when she says "Don't you understand that I can't," Jareth is standing in front of a tall tree. But in the next shot, the tree has gone. There are just tree limbs and branches behind him, but the tree has disappeared. (00:13:32)
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.
Continuity mistake: During the battle in the Goblin City, a Walking Cannon fires a shot at one of the rocks. When the rock shatters, the roof behind it and a jar at the right edge of the screen suddenly shift their positions - slightly but visibly.
Audio problem: When in the Goblin's house, Sarah chucks a plate of food in a Goblins face and says 'Hungry?' but her mouth doesn't move when she says this. (01:20:05)
Continuity mistake: When Sir Didymus is being chased in the goblin city by the guards, the distances between the guards and Didymus, and the actual guards chasing him, changes frequently between shots. (01:17:30)
Continuity mistake: Depending on the angle of the shots, things on top of the changing table and its shelves behind Toby's crib change position or disappear. The string toy that hangs in Toby's crib changes and also changes position. The wicker hamper basket changes position and the clothes that hang from it change as well. (00:07:00)
Continuity mistake: Hoggle wears a small orange jacket, and a brown leather belt (which has many objects attached to it, such as keys, a pipe, etc.,) which is attached to at the top, on the right side of his jacket, which runs diagonally across his body. However when Hoggle says "Me? I wouldn't go either way," the whole top portion of his body is visible, and you can clearly see that the leather belt is not attached at the top of his jacket. It seems to have gone in this shot. However after he says "You know your thing, you take to many things for granted," the belt is now back, reattached to the top of his jacket. (00:16:55)
Continuity mistake: When Sarah goes into Toby's room, and picks up Lancelot, she puts the teddy on her parents' bed next to her, then sits down. In the next shot, the teddy is behind her on the bed and it can be seen when she stands up. (00:07:00)
Continuity mistake: When Sarah wakes up in the junkyard, there is a wide shot, then a closeup of Sarah holding the peach. Between the two shots, the way Sarah holds the peach changes. (01:07:10)
Visible crew/equipment: After Sarah calls out "Toby!" in the Escher stair room, she jumps off the ledge. She then drops downward and lands amongst a variety of stone objects that drift all around her. The lines that the stone objects hang from are seen. (01:30:30)
Continuity mistake: When Ludo is hanging upside down, while the nasty little guards taunt him, the line that is tied to the tree root is seen and the knot end is different throughout these shots. (00:41:55)
Answer: To add to that, the other door was supposed to lead her to certain death, and technically the oubliette wasn't exactly certain death.