Sorry if this is super late and useless, but they actually film long into the season. Season 3, for example, was re-written because there was such an uproar about the character of Lauren Reed. About 4-6 episodes in, they re-wrote her as a bad guy, which she was not originally supposed to be. Then they started re-shooting. They pretty much try to stay between 5-7 episodes ahead of the viewers, with the ongoing possibility of continuing to shoot deep into the current season just in case
(ie: staying up on current events, bad ratings, etc.)
I just seen on this other website that they might not be premiering Season5 of Alias until 2006, due to Jen's pregnancy...Don't know if this is true, but it is what i read!!
This is where i read it: JenniferGarner.fanhost.comhttp://