SPOILER WARNING: This article contains spoilers for "Promises Kept," the latest episode of Arrow.

Arrow Season 6 just broke the fourth wall -- sort of. In "Promises Kept," the latest episode, Oliver returned home from his trip with Deathstroke to find Felicity and his son William playing a video game familiar to DC Comics fans: Injustice 2.

Although William put down his controller almost as soon as Oliver walked through the doors of the apartment, the camera lingered long enough on the screen to catch a glimpse of his gameplay. Either he or Felicity had been playing as Sub-Zero, one of the Mortal Kombat characters that feature in the game, in the Gorilla City arena.

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Of course, Injustice 2 largely focuses on DC Comics characters, from Batman and Superman to -- yes -- Green Arrow and Black Canary. The minds behind the show must have thought that would have been a little too on-the-nose for a show with a tone as serious as Arrow, but eagle-eyed fans should be able to recognize the game.

Starring Stephen Amell as the Emerald Archer (well, not currently), Arrow airs Thursdays at 9pm ET/PT on The CW. The series also stars Emily Bett Rickards, David Ramsey, Willa Holland and more.