Now that Avengers: Endgame is out on digital and Blu-ray, fans can pore over the film as many times as they want to hunt down the film's secretive Easter eggs. Already, Marvel Cinematic Universe devotees have spotted a nod to Spider-Gwen, a reference to the Marvel Multiverse and even a possible allusion to an ancient battle glimpsed in Thor: The Dark World. And now, thanks to a visual effects reel, another Easter egg has been revealed.

The video, by visual effects studio Cinesite, includes the scene in which Tony Stark will meet his father Howard at the Camp Lehigh Army base in 1970. At the beginning of the sequence, Tony stumbles into the underground bunker in search of the Tesseract. In the background, there are rows of green computer screens. While it's almost impossible to make out what the screens depict, the VFX reel reveals that, in the distance, is a display of Arnim Zola's face.

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Avengers Endgame Zola Easter egg

Arnim Zola debuted in 2011's Captain America: The First Avenger. Played by Toby Jones, Zola was the chief scientist of Hydra, and the Red Skull's right-hand man. Zola was eventually taken into custody by the Allies' Strategic Scientific Reserve, and we learned in 2014's Captain America: The Winter Soldier that, thanks to Operation Paperclip, the Swiss scientist defected to join S.H.I.E.L.D.

However, as we now all know, Zola was secretly working for Hydra. What's more, he found a way for his consciousness to survive beyond his body. After death, Zola's mind lived on in a giant computer housed beneath Camp Lehigh. The bunker was first shown in The Winter Soldier, in a scene that ends with the destruction of the computer -- and the apparent death of this second version of Zola.

When Tony locates the Tesseract in the camp's bunker, in 1970, he is startled by his father, Howard, who is calling out for Arnim. At the time, we didn't know whether Howard was talking to the man or his computer alter ego. However, this Easter egg indicates Howard was talking to Zola's consciousness inside the bunker.

Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr. as Iron Man, Chris Evans as Captain America, Mark Ruffalo as Bruce Banner, Chris Hemsworth as Thor, Scarlett Johansson as Black Widow, Jeremy Renner as Hawkeye, Brie Larson as Captain Marvel, Paul Rudd as Ant-Man, Don Cheadle as War Machine, Karen Gillan as Nebula, Danai Gurira as Okoye and Bradley Cooper as Rocket, with Gwyneth Paltrow Pepper Potts, Jon Favreau as Happy Hogan, Benedict Wong as Wong, Tessa Thompson as Valkyrie and Josh Brolin as Thanos.

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