Grant Gustin shares first picture of Supergirl cross over 

Just over week ago, we learned that the much rumoured crossover between The Flash and Supergirl was officially going to happen. Along with the 90’s Flash, Kara Zor-El is very briefly glimpsed during the next episode of The Flash, which airs next week on Sky One. 

Grant Gustin (The Flash/Barry Allen) took to Instagram to share the first photo of him and Melissa Benoist (Supergirl), both wearing their superhero costumes. Barry Allen and Kara can be seen on set, while shooting “World Finest” — the eighteenth episode in the first series of Supergirl.

I fully expect The Flash to travel to an alternate Earth, where Supergirl exists. Trust me, it’s only a matter of time before Arrow shows up in Gotham.