camera used?

Well of course they used digital, and even a low level Red One is going to have a hard time creating DOF with a cheap set with bad lighting. Notice the one time they are walking outside, or when she is on a bus it looks pretty decent. And I think you mean that there is ONLY shallow DOF, where you would normally want deep DOF? Anyway, with the digital you can usually pull it off by zooming in all the way and bringing the camera way back, which is impossible to do in those hallways. I don't think they really tried to hard if you ask me.