The scene where Adam first puts on the weights and flips upside down is actually shot in a room that is suspended in a big giant wheel. The room itself, and everything inside it, moves 360 degrees. The camera moves with the room, so you can't tell if the room is moving, but you can see him flipping upside down.
For the Floor Zero scenes, Production Designer Alex McDowell's team built two sets, which sat side-by-side, as if the screen had been sliced down the middle and folded open. When characters between the two worlds interact, the "down" scene takes place on one set and the "up" scenes takes place on the other, simultaneously.
One set featured an upside chandelier. "We built three quarters of a chandelier, not the very top, but everything else, (and there) was a steel rod up the center holding it down," says Production Designer Alex McDowell. "We had to wire up the crystals so that they looked like they were hanging."