So the producers say that the ending to Lost is right there in front of us, so I have a theory which wouldn’t make sense afterwards unless the characters had amnesia or brain damage: They wake up, like a bright light or something, back into 2004 (before the crash). They have no idea what happened or where they are (well, Juliet might know where she is) and so they’re confused. Then they realize that it was their destiny, all along, to go to the island, so they make themselves go to the island; that’s why Ana Lucia went with Jack’s father to Australia, and that’s why Jack yelled at the ticket agent to get his father’s coffin on the plane, and that’s why Hurley “needed” to make the flight! Let me know if you think that this is crazy enough to work.
P.S. Yeah, on some parts it can't work, but I was thinking the other night, why would Hurley want to get on the plane so bad? Yes, it can't work, but it's the only theory that I can think of.