Supergirl Season 4: 5 Easter Eggs & References You Missed In ‘O Brother, Where Art Thou?'

5. Superman: Red Son

The episode's opening scene may just been the biggest gift-giver of them all.

As we were introduced to Lex Luthor through a flashback to four years ago, we couldn't help but notice an eerie orange-tint that had descended upon the world as a terrified Lena Luthor watched it tear itself apart. As Lex proudly took credit for the madness that had enveloped below, Lena begged him to undo what he had started because "the world couldn't live under a Red Sun".

Superman: Red Son was an Elseworlds tale that looked at what would have happened if the Man of Steel had been raised by the Soviet Union instead. However, it also happens to be what the current season of Supergirl is based on as the show is doing its own adaptation with a Red Daughter version of Kara who showed up in the Season 3 finale.

Perhaps the most timely Easter Egg in the episode, Lena wasn't just referring to Lex's masterplan to de-power Superman with a Red Sun, as her words referred to one of the most iconic Superman stories of all time and the foundation of Supergirl's current season.