Ruth dates Zefram Cochrane! And he is apparently already constructing a bomb shelter, in order to survive World War III and then invent the warp drive... Hilarious in Hindsight: One season before, Ruth already took a self-help seminar presented by the Borg Queen.
Before he's hired at Dunder Mifflin, Dwight Schrute does a stint as the awkward apprentice Arthur Martin.
Crewman Daniels shows up as a rather camp member of the gay chorus that David joins.
Zachary Quinto makes a brief appearance as one of Claire's class members prior to Olivier's entry.
Mike Nelson apparently left his home town of Twin Peaks to work for Kroehner's.
Among the Fisher's "clients" are:
Dr. Phlox, who dies by the hand of his wife. (Probably statistically a common cause of dead among Denobulans, since they have so many wives...)
Ted Mosby, whose corpse gets found in a crashed car decades after the accident that killed him happened. During his funeral, attended by his children who hardly knew him, his "ghost" ironically remarks that he would have been an awful dad.
Claire's fellow student and temporary love interest Edie used to be an innocent choir's girl called Heather. Oh, and she almostseduced Kevin Spacey.
During her sister's vicodin withdrawal Ruth befriends Annie Wilkes.
Cristina Yang is a porn star that attends the funeral of a late colleague.