Visible crew/equipment: At the start of the film, when Bowie sings the word, "Underground," the last word of the song, it's just at that moment the screen goes from black background to a backdrop of trees in the real park, which is the same moment the animated owl turns into a real owl, the wire attached to the real owl's left foot is visible. There is a jess (strap) around its left foot, that is also clearly visible when he lands on the obelisk in the park. (00:02:40)
Visible crew/equipment: Sarah's father's bedroom back doors open up and the owl flies in towards Sarah. While in the doorway, the lines that the owl hang from are visible. (00:11:45)
Visible crew/equipment: First in Sarah's father's bedroom, as Jareth holds and flits the crystal back and forth in his hand, then at his castle as Jareth holds the crystals while sitting in the window and in the scene with the drifting stone as Jareth holds one crystal, objects are reflected upside down within the spheres. Studio lamps and its lights are visible, as well as reflections other than Jareth and Sarah. (00:12:40)
Visible crew/equipment: Jareth says, "Sarah, don't defy me," and tosses the snake at her neck. In the next shot facing Sarah as she holds the snake, a crew member's hand is seen holding the end of the 'snake' below her right shoulder. (00:13:25)
Visible crew/equipment: When Hoggle is spraying the fairies, before he sprays fairy number 58, two thin black wires making the fairy fly are quite visible. (00:15:15)
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)
Visible crew/equipment: Just after Jareth kicks the furry little creature way up towards the camera, he sings, "Jump, magic, jump..." To his left, when the little guy 'leaps' high into the air, in front of Jareth's throne, the wires attached to both sides of his shoulders are visible. (00:23:55)
Visible crew/equipment: After the Goblins sing, "Slime and snails... Thunder or lightning," they all sing, "Jump, magic, jump..." and when the Goblin, with the red scarves at his waist (same one as earlier shot, also visible in later shot), lands back on the ground the wires attached to the back of his shoulders are visible. Then in the next wide shot, the wires attached to the back of the waist on the tall Goblin with the long hair, are visible. (00:25:40)
Visible crew/equipment: While falling through the well of hands that lead to the oubliette, wires are visible attached to Sarah. Mostly noticeably when one hand says "Would you like us to let go?" and as she is dropped, wires are seen attached to her arms. (00:27:50)
Visible crew/equipment: As Hoggle and Sarah climb the ladder after being chased by the cleaners, Hoggle says to Sarah 'I'm a coward, and Jareth scares me.' As he says this you can see a wire attached to him. (00:35:55)
Visible crew/equipment: When the second rock that Ludo calls rolls towards Sarah, the wire attached to it is visible. (00:40:55)
Visible crew/equipment: When Sarah and Hoggle are in the Bog of Eternal Stench and they almost fall in, look in the top left hand corner of the overhead shot and you will see a boom microphone. (Only on Blu-ray edition). (00:53:40)
Visible crew/equipment: Just after falling into the Bog of Eternal Stench, the duo are moving along the ledge. As it breaks away, there is an overhead shot where you can see a white and blue piece of equipment at the top left corner of the shot. I don't know what it is but it's not in the next shot so it's not something natural to the Labyrinth. (00:55:45)
Visible crew/equipment: When Sarah and Hoggle slip off the ledge at the Bog of Eternal Stench, Ludo breaks their fall below. As they fall, in the wide shot, the lines holding Sarah and Hoggle are visible. (00:56:20)
Visible crew/equipment: After Sarah meets Sir Didymus at the Bog of Eternal Stench, Sir Didymus climbs on Ludo's back. While he is up there, the bottom portion of Didymus' right hand 'puppet control rod' is seen being controlled on Ludo's right side. The top portion of his right hand control rod is seen many times throughout his shots. His left hand control rod is concealed as his staff. (00:58:20)
Visible crew/equipment: At the Bog of Eternal Stench Ludo summons the rocks with his howling, and we then see one shot of a rock rolling forward. You can see a thick wire attached the centre of the rock, pulling it forward to make it roll. (00:58:40)
Visible crew/equipment: After the Masquerade dream scene, you see Sarah falling on top of a dump. When she falls, you can see the wires attached to her letting her down. (01:09:30)
Visible crew/equipment: When Hoggle jumps off the wall's ledge onto the gate's metallic robot, the lines attached to Hoggle are visible. Hoggle then yells, "Get out of there!" to the controller of the giant robot. As he leaps on top of him, and when Hoggle says, "My turn now," the lines attached to Hoggle are seen again. (01:16:50)
Visible crew/equipment: A cannonball goes flying, when Sarah and the gang are at the Goblin City (The one that says "I hit something? Yes? No?") and as it heads towards the wall, you can see the wire it's attached to. (01:18:30)
Visible crew/equipment: As Sarah, Ludo, Hoggle and Sir Didymus finally walk into Goblin City and reach the fountain, they face the stairs with the surrounding spike walls. In the next two shots, the Goblins appear behind the spiked walls, and in the second shot, on the right, a puppeteer's arm - wearing a short sleeved blue shirt, is amusingly visible under his Goblin soldier puppet; the top of the head of another puppeteer is visible to his right. (01:19:55)
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.