Just when I thought that Lost couldn't get any better, they come up with an amazing episode. We all know that they are going to go back to the island - but they way they put it together is brilliant. Each character has their own different reason for being on that plane and I'm sure we'll be told in future episodes in "flash-back" type episodes, like we had in the first seasons.
We were told that the situation on this plane needed to be similar to what it was on the first plane that crashed.
These are the similarities I noted:
1) The most obvious, Jack's father's shoes inside a coffin
2) A guitar (Charlie had it in the first crash - now Hugo has one)
3) A prisoner and an FBI agent (And I'm sure a suitcase was there)(one male and one female)
And I'm sure there were others.
Of the people that were supposed to be there, but weren't seen on the plane: only Aaron. Desmond was never on the plane although that doesn't explain why Lupitas was the pilot for this flight.
I'm sure we'll find out what happened to them before the end of the season. I'm looking forward to the rest of the season - it's been fantastic so far.