tsimer, that's one of the reasons i was considering this afternoon.

Some of the other things i thought about:
-a metaphor (or some term...i don't know) of the life Jack had with Sarah and without...or in real life and on the island...who knows.

-concerning the two seperate locations of Jack and Swayer/Kate (although i don't give this one much thought...cause their obviously not all that far apart).

-the difference between the Others camp and the Losties Camp (although we didn't see anything of the Losties camp).

But i think i give the most credit to the difference between how the Other make themselves appear to the Losties and how they really are. Just a thought