Day 4: 1:00 A.M.-2:00 A.M. - S4-E19
Continuity mistake: At the very end of Episode 18, Jack knocks out Joe Prado after breaking his thumb and getting information from him. At the very beginning of Episode 19, we see Prado already being treated for his injuries, with a hand splint, and nurses checking his head, within the CTU clinic. Even if you factor in the opening recap sequence at the beginning of every episode, that means that Joe Prado regained consciousness, Jack unhooked his handcuffs, and dragged him back to CTU in three minutes or less.
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.