Can someone explain to me what was actually happening in that episode and what it might mean for what was done last season?
I think it was supposed to show us how awful everyone's personality is (well, Walter and Olivia's anyway) without Peter's involvement, and what a crucial impact his absence has on the world. Oh, and that jumping between universes now just requires a room with a burst of lights in the floor.
With the exception of the room bit, it pretty much failed to do those things, though. Walter's always been an on-and-off dick, Olivia's always had the personality of a piece of wet cardboard, and the changes that should
have occurred with Peter's absence are what's actually absent.