Look! Up in the sky! Its a bird! Its a plane! Its a doctor from Seattle!

That reference makes no sense in a vacuum, but it makes perfect sense if you watch both Supergirl and Greys Anatomy and are hip to the fact that the second most important character on the show is played by Chyler Leigh, who was on Greys in a former life.

And this isnt even the first time the show has referenced one of its actors past work.

Sharp-eared Supergirl viewers on Reddit caught the reference on a recent episode when Leighs character was talking to another woman, who asks, So you were a doctor before you joined the FBI? Leighs character responds, I had a job, actually, up in Seattle for awhile.

That couldnt have been a coincidence, and viewers got a kick out of the in-joke, with one person making their own in-jokes: What made you leave Seattle? Was in shooting and then a plane crash Seattle! Well the plane crashed on the way away from Seattle Were you really a doctor Surgeon Specialty? It was going to be brains.

Then another person pointed out I just realized after seeing this post, her name is Alexandra Lexie Grey on Greys Anatomy and Alex Danvers on Supergirl. That one must be a coincidence. Probably? Either way, one other viewer finally saw the light, saying OMG NOW I REALISE WHERE I KNOW HER FROM!

Leigh had been on Greys Anatomy from 2007 to 2012 playing Lexie Grey, the half-sister of the main character Meredith Grey. The newer Grey earned the dubious distinction of being named the most pointless character on the show because, as one fan put it, All she did in the end was break up with Mark and then sleep with the next available guy until she died.

Lexie died a particularly traumatic death when she perished in a plane crash at the end of season 8. In real life, Leigh said she was leaving the show to spend more time with her family, and her departure wasnt one of the stormier ones that Greys Anatomy is rather infamous for. However, it wasnt long after she left Greys that she got the gig on Supergirl in 2015.

In the superhero show, Alex Danvers is the title characters adoptive sister in that her family took Kara Zor-El in after she crash-landed on Earth and helped her become Kara Danvers. When Kara decided to become a superhero, she joined forces with her sister, who is the director of a government agency that defends Earth from alien forces the kind Supergirl keeps tangling with.

Supergirl is played by Melissa Benoist, whom viewers met on Glee in 2012, when she was one of the new batch of kids that arrived at McKinley High School after the seniors graduated. Benoists character, Marley Rose, was a poor shy girl with a strong voice seen as a new Rachel, the Glee club star (Lea Michele), who had moved to New York City.

After Supergirl started in 2015, Benoist gave an interview to EW, (one where she references an eye injury that she later revealed was the result of domestic violence) where she was asked about doing a musical episode. She replied, Its kind of a running joke though because Im not the only one on the show that does. Jeremy Jordan is an amazing singer. Mehcad Brooks is a rapper. Chyler Leigh is a singer. I think David Harewood sings as well. Weve all joked that it would be funny. I dont know if the producers have seriously thought about it.

Eventually, they did. Grant Gustin, who plays the Flash on Supergirls sister show, had also appeared on Glee. This led to a crossover Flash episode that gave Benoist and Gustin excuses to sing. Benoist sang the standard Moon River while she and Gustin at the hands of a villain called The Music Meister, who was played by Darren Criss, another Glee veteran.

Leigh hasnt sung on Supergirl, but she did sing Anna Nalicks Breathe (2 AM) on the musical episode of Greys.

The rest is here:
'Grey's Anatomy' Fans Still Can't Handle This 'Supergirl' Shout-Out - Showbiz Cheat Sheet