Humans are incapable of securely storing high-quality cryptographic keys, and they have unacceptable speed and accuracy when performing cryptographic operations. (They are also large, expensive to maintain, difficult to manage, and they pollute the environment. It is astonishing that these devices continue to be manufactured and deployed. But they are sufficiently pervasive that we must design our protocols around their limitations.)
Charlie KaufmanThe biggest thing that I came across, right off the bat, was that you can't shoot this like a regular movie with multiple takes. You have to, because it's such a protracted process, break it down to the frame and pretty much get one shot.
Charlie KaufmanAnd also the idea of not making it apparent that it's different from the rest of the film, even though there are visual differences, the audience is supposed to think that they are with him when he wakes up in the morning.
Charlie Kaufman