The multiversal anomalies started before the power outage, only no one noticed.
At one point, Laurie asks Mike what he does, and Mike responds that he's an actor who had a recurring role in the popular 1990s teen paranormal drama Roswell. Now, this is obviously a little in-joke about the fact that Nicholas Brendon, who plays Mike, was actually a regular in a certain other popular 1990s teen paranormal drama — except that Laurie goes on to comment in astonishment that she used to love watching that show, but doesn't remember Mike's character being in there at all. Note also that the sudden cuts to black (hinted to be switches between different realities) start before the power outage that kicks off the bulk of the drama — and that all of the characters arriving at the dinner party arrive at different times. Perhaps they all come from slightly different realities from the beginning, and "Prime" Laurie actually comes from a world where Mike really wasn't in Roswell...- Mike also remembers Laurie as having done "Spanish Yoga" which she vehemently denies.
- As I recall, he remembers her teaching yoga, which she denies. She later says that she "had to do a lot of yoga" for several days after a sexual encounter with Kevin, suggesting but not guaranteeing that she's a different version.
- Mike also remembers Laurie as having done "Spanish Yoga" which she vehemently denies.
DNA testing will show Em is indeed an exact duplicate the final house's Em.
Em will be exonerated. Stories of similar things happening elsewhere, and the previous comet stories plus Hugh's physicist brother will step in to help.