Because, wow, I'm only five episodes into the DVDs and apparently there was a lot I didn't know.
I thought Multiplex was a take-off on Multi-Man (a Challs of the Unknown villain) or MAYBE Riot, but - nope! - wikipedia sez Firestorm villain.
I know the Mist fought Starman and Black Canary in Brave and the Bold, but I don't remember him from the Starman Archives. (Or is that just my awful memory?) I'm 99% sure he was a Golden Age villain, and 95% sure he never fought B.C. before Brave and the Bold 61.
Plastique showed up in crowd scenes in Infinite Crisis or one of those damn crossover books, but I don't know where she originally appeared. Something in me is saying Outsiders? Was she the one hanging out with the Suicide Squad for a couple issues?
Wade Eilling was a Captain Atom villain, but I only know that from reading Back Issue - I've never read the Cary Bates series.
Hmmmm... there's a Caitlin (Snow?) who's dead excuse me "dead" boyfriend is Ronnie.
Dangit, doesn't the Flash have a deep enough pool of villains that they don't have to borrow characters I barely know? I actually had friends asking me comic book questions I couldn't answer! It was embarrassing!
(Pretty dang good show, though!)