There are several notable elements to the set design - one of the most significant being that the central platform where the action takes place is surrounded by water on 3 sides (not unlike the city of San Francisco, and also conveying a sense of isolation). They only really make use of it once, but it’s a striking effect.
And the other most surprising element is a rear wall made of crumpled paper (letters), that’s revealed in act 2.
The glass panels of the floor are also sometimes lit from underneath, and there’s one moment of simple, but essential use of projections.