'Extra' On the Set for the ‘The Flash’/’Supergirl’ Crossover!

A supersized superhero event airs tonight and only “Extra” was behind the scenes as Supergirl and The Flash joined forces for the special crossover episode.

Check it out above!

Watch “Supergirl” tonight at 8 p.m. on CBS, and “The Flash” on Tuesday at 8 p.m. on The CW.

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