12:00 Midnight-1:00 A.M. - S1-E1
Character mistake: When Jack subdues Mason he proceeds to check his pulse to check Mason is still alive. When taking the pulse however Jack uses his thumb. This is not how a pulse is checked, as the thumb has it's own pulse and would therefore give Jack's pulse instead of Mason's. Being ex-Delta Jack would know this and not make the simple mistake. (00:22:10)
Chosen answer: Nobody knew, not even the writers, until at least halfway through the season when they were writing the end. They wanted to keep all options open.
Nick N.