The final episode of St. Elsewhere revealed that all of the action of the show took place in the mind of an autistic child. Two detectives from Homicide: Life on the Street investigate a doctor from St. Elsewhere. Thus Homicide is a fiction. And so are 280 other shows that are connected to those two shows through crossovers and references. This page contains a map of all the crossovers, encompassing such disparate shows as Doctor Who, The King of Queens, and Leave It to Beaver. Wonderful.