I think in the whole of season 5, Jack Bauer's longest lines, his acting na acting moment, was during the final episode. In the previous hours, he would have little to say (and it was always the same line or context!). But what he had to say in the final scenes is probably the best moment for this season:
Note: MAJOR SPOILERS. You've been warned.
And that is why, for all it's impossibilities and incredible storyline, a scene like this makes me addicted to this show for the last five season.
Season 5 - Day 5: 6:00am-7:00am
Original Airing: May 22, 2006