Huh. Um, I'm going to have to cop to the same -- we did an alternate timeline thing in Buffy as well. Our Buffy series was one where the PCs were all young IT professionals in Silicon Valley who eventually organized themselves as a startup company, "Vampster". The episode was mid-way through our second season. Below is the summary I wrote for the players of it (which might not be too comprehensible to non-players).
"A Practical World"So, what happened in mine was that a computer program went haywire in a fight. As a continuing plotline, there was a set of business calendar/scheduling software which was capable of tapping into someone's Fate lines.
What happened was that the three normal-human PCs -- Chip, Roberta, and Carlos -- all found themselves in an alternate timeline. In the timeline, the gist was that they had mostly gone on to relatively normal lives. However, their friends with superpowers had gone to fighting evil in a purely serious manner and were organized as a gang ("The Stakes") rather than as a company.
It ended with them finding the means to leave and go back to their own timeline.