Day 4: 1:00 P.M.-2:00 P.M. - S4-E7
Continuity mistake: When we first see the map of the powerplants that are successfully shut down (green) all the plants in Minnesota are green. Towards the end, however, one of them is shown flashing red, meaning it has not been shut down.
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.