Continuity mistake: As they are sitting around, planning the next job, Cobb is wearing a blue shirt, of which he rolls up the right sleeve repeatedly.
Continuity mistake: When Arthur is shot in the head, at first there's no bullet hole in his head, but in the next shot there is.
Revealing mistake: When the chase in Mombasa has just begun, the camera is moving in front of Cobb at one point. Notice how the people behind the camera are moving into Cobb's paths, despite the fact that they weren't there a second ago?
Continuity mistake: As Cobb is explaining to Ariadne the importance of imagining new places to create dreams, the positions of his head, arms and hands change between shots.
Chosen answer: The details are never explained in the depth, but all the dreamers are connected via the briefcase, so it seems likely that the briefcase acts in some way as a networking hub for them to share the dreamspace.
Tailkinker ★