I'm still on the fence about whether or not Nimoy is evil. The show hasn't given any indication on why the
other Fringe team was at the park, unless they were tipped off.
What I loved about this finale is that Walter basically assembled the X-Men to crossover, and how the writers have been able to juggle two sets of characters without making one side good and one side evil. You can totally justify the
other world's actions; in fact, everything has been our side's fault so far.

EDIT: Blue, who would you bang - blonde Olivia or red hair Olivia? The red haired Olivia seems like she's cockier, probably better in bed too.