As you may have noticed, Alcatraz and House were preempted by the rescheduled Daytona 500 today. (It was rained out yesterday.) It's not completely clear what this will do to the schedule. A few people have noted that the Fox site says Alcatraz will be on Saturday at 11, but that's a regular repeat timeslot, and the repeats are a week behind, so the one scheduled for this Saturday is the episode that aired last week. Alcatraz was supposed to have two episodes on 3/5, one each on 3/12 and 3/19, and a two-hour finale on 3/26. So . . . I have no idea what they'll end up doing with this extra episode, especially as they now have an extra House episode to fit in too. They might just leave it on Saturday 3/10, or they might push stuff back a week, or do something completely different. It might depend on whether they've already given up on the show or not.
Er, that was a very long-winded way of saying that I have no idea what's going on, but don't necessarily assume the episode that was supposed to air tonight is on this Saturday, because as of right now, it isn't. And if I do find out, I'll let you know!
Update: This tweet from the show's official account confirms that there will be two episodes next week, but that was already planned. Unclear on where the extra episode is going.