Joe and Anthony Russo -- collectively known as the Russo Brothers -- recently uploaded a behind-the-scenes picture of them on the set of Avengers: Endgame with none other than Epic Games creative director Donald Mustard. Turns out Mustard wasn't just visiting for the day, as he actually played an extra during the movie's climactic final battle against Thanos. The Russo Brothers shared the image during a recent Quarantine Watch Party of Endgame, which celebrated the film's first anniversary.

During the promotion of the movie, Epic Games’ Fortnite featured a tie-in with the film, adding Thanos, the Chitauri, and legendary weaponry associated with the Avengers themselves, including Captain America’s shield, Iron Man’s repulsors, Thor’s hammer, Mjolnir, and even Hawkeye’s bow.

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But their relationship works both ways. Not only did the Avengers feature in Fortnite, but gameplay from Fortnite would also appear on the big screen during a key recruitment scene in Endgame. As Rocket Racoon and Hulk try to motivate Thor to rejoin the Avengers in their mission, it’s revealed that Thor has developed a newer, more personal rivalry with an enemy known as Noobmaster -- an online rival Thor has been battling with on Fornite.

Prior to Fortnite’s tie-in with Endgame, the game also had a crossover with 2018’s Avengers: Infinity War, giving it a great base to build from for their Endgame collaboration. With Epic Games and Marvel seemingly cultivating a long-standing relationship, it may only be a matter of time until even more Marvel heroes, iconic objects, or weaponry appear in the popular battle royale game.

Avengers: Endgame is available on Blu-Ray, DVD, and streaming services.

MORE: Russo Brothers Reveal A Ton of Avengers: Endgame Behind-the-Scenes Footage