It's up there but I still think the best one is when they find out Ethan isn't on the manifest and we find out they're not alone on the island and he's about to do something bad to Charlie and Kate.
That was just a "WTF!!!" moment for me.
Woah, woah. Let's not go crazy here, it was a decent episode but it was no way near as good as The Constant, every one of the season finales, the Pilot, Walkabout and The Man Behind the Curtain
There have been certain moments that stick in the mind, like finding out about Ethan and the line, "We're going to have to move the island", but I can't think of any episode that has asked and
answered as many questions as "The Substitute" did.
I accept all the season finales are superb too (and 'The Constant'), but still think this episiode is right up there - time will tell if tis stil up there at the end though.