Moon (2009) via Moon (2009).
Interesting story and fun to have the answers revealed over time. However, I’ve seen this before – I didn’t remember it at first.
That wasn’t bad, but it made it kinda slow.
So the flaw is that if you figure it out, it’s a bit of a drag. Ideally, the implications and such of the twist would keep things going, but I don’t think they pull it off.