The Menger Sponge (zero volume, infinite surface area) design for the outer shell of the DEVS apparatus was brilliant. For those not familiar with it there are numerous youtube videos exploring it.
I knew I recognized Ms. Mizuno but it took awhile to place her as the dancing mute android in Ex Machina. As the main protagonist I thought she was excellent. Nick Offerman, Jin Ha and Alison Pill filled out a solid cast.
Using the interpretations of quantum theory to move the plot along keep me very interested including the surprising ending. I think it would be possible to take the concept even further in a sequel but I know that's not going to happen.