I just rewatched this episode and its pretty much the flash sideways explanation. I think they all have become unstuck in time and becoming each others constants or something flashes them back.

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.