Surprising DC Superhero Makes Cameo on "The Flash"

Warning: Spoilers follow for this week's episode of "The Flash," "Welcome to Earth-2."

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As Barry Allen traveled through the Multiverse on tonight's episode of "The Flash," we caught a peek of Melissa Benoist's Supergirl.

Here's a screen cap of the brief glimpse -- from the "Supergirl" pilot -- of Benoist's Girl of Steel in-flight:

Because Barry's travelling through the Multiverse, this could confirm that "Supergirl" takes place in an alternate Earth -- as opposed to the one shared by "The Flash," "Arrow," and "Legends of Tomorrow."

If "Supergirl" is on another Earth, that means the upcoming "Flash"/"Supergirl" crossover involves more alternate-reality adventure for Barry Allen -- and the first we've heard of the Multiverse existing in "Supergirl."

"The Flash" airs Tuesdays at 8/7c on The CW.

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