Inception (2010)

Revealing mistake: When Ariadne is pulling the two huge mirrors close together underneath the bridge with Cobb, watch her when she is closing the second mirror. She steps over something even though there is nothing present for her to step over. There must have been a green screen frame there for her to step over.

Cobb: We need the heir of a major corporation to dissolve his father's empire.
Eames: Well, you see, right there you have various political motivations and anti-monopolistic sentiment and so forth, but all that stuff is at the mercy of your subjects own prejudice. What you have to do is start at the absolute basic.
Cobb: Which is what?
Eames: The relationship with the father.

Trivia: The "architect" Ariadne's name is taken from the character in Greek mythology who gives a thread to Theseus so he can find his way out of the Minotaur's labyrinth.

Question: How do the people in the film share a dream? I understand that the briefcase contains sedatives to put everyone to sleep, but how do they get inside a certain individuals dream? How do they end up being in the same dream together?

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