CBS has revealed an official poster and for the upcoming  Supergirl episode that features a crossover with The Flash, which is a homage to the cover of Superman #199.

And here’s the official description for the 18th  Supergirl episode, titled “World’s Finest” which confirms what many fans were theorising – that the CW’s The Flash and CBS’s Supergirl are set on different worlds within the multiverse (which’ll handily help cut down on a lot of potential continuity problems):

“Kara gains a new ally when the lightning-fast superhero The Flash (Grant Gustin) suddenly appears from an alternate universe and helps Kara battle Siobhan, aka Silver Banshee, and Livewire in exchange for her help in finding a way to return him home.”

Supergirl returns to the UK on Sky 1 on 1 April.

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