Episode Title: World’s Finest
Original Airdate: 03-28-2016
Otherwise known as The One Where The Flash Guest Stars. If it’s possible for two shows to poke meta-referential fun at each other, “World’s Finest” does the job well. It has to be remembered that at one point a crossover between CW’s The Flash and CBS’s Supergirl was never even on the table: producer Greg Berlanti stated that bringing either hero into each other’s respective universes was a pretty big long shot, and yet here we are, 18 episodes into Supergirl’s first season (and a dozen or more into Flash’s 2nd) and both Barry Allen and Kara Danvers trade interdimensional references and powers in one of the “fun” episodes of the series’ run thus far.