From Ausiello

Question: I keep hearing about this groundbreaking 15th episode of Lost that features none of the series regulars. Can you spill any dirt on why that might be? —Brittany

Ausiello: It’s not completely accurate to say there are no series regulars in it. It would be more accurate to say it’s really light on series regulars. As far as why, let’s just say it’s a big mythology episode and leave it at that.


source: Ausiello