Robert Downey Jr. Says Actors Were “Dropping Like Flies” While Filming ‘Avengers: Doomsday’

Robert Downey Jr.’s return to the Marvel Cinematic Universe has been one of the most closely watched stories of the year, marking the actor’s first time back on screen since Tony Stark’s death in ‘Avengers: Endgame.’ This time, though, Downey isn’t reprising Iron Man at all, instead stepping into the role of Victor von Doom, the hooded, armored villain at the center of ‘Avengers: Doomsday,’ a casting reveal that shocked fans when it first broke at San Diego Comic-Con.

That transformation has come with its own physical toll, according to Downey himself. Reflecting on the production in a recent interview, Downey described the shoot as brutal in ways that went beyond simply learning a new character, largely due to the demands of the elaborate Doctor Doom costume he wore for months on set.

Downey said filming felt “very much like a series of sprints,” explaining that the process was “really taxing just physically because of the nature of these heavy costumes and stuff.” He went on to describe the toll the heat took on the cast and crew, recalling, “It’s like 94 degrees and 88% humidity. People are going to start passing out… I didn’t want to be the first man down on Doomsday,” before adding that he watched colleagues on set “start to drop like flies” under those conditions.

Downey’s comments line up with what’s already been reported about the sheer scale of his Doctor Doom look. According to Outlook Luxe, the costume relies on heavy armor, structured proportions, and a full metallic mask that obscures Downey’s face almost entirely, a deliberate design choice meant to convey power through concealment rather than the sleek, recognizable style associated with his Tony Stark wardrobe.

That level of costume complexity appears to have directly shaped how production approached filming schedules. Downey explained that once the heat and physical strain became clear issues, the team adjusted their overall filming program, a change he credited with helping him avoid the kind of exhaustion he saw affecting others around him during the shoot.

The physical demands of the role fit into a broader pattern of dedication Downey has shown toward reinventing himself as Doctor Doom. According to Variety, Russo brothers Joe and Anthony described Downey as deeply immersed in the character during preproduction, noting that he had been actively writing backstory material and contributing costume ideas well before cameras started rolling.

That commitment extended into the film’s marketing rollout as well, with Downey making a memorable, mask-off reveal of his new role at San Diego Comic-Con, delivering the now-famous line “New mask. Same task,” according to The Hollywood Reporter. The Russo brothers have since called the finished Doctor Doom costume their favorite of any suit across the five Marvel films they’ve directed.

With ‘Avengers: Doomsday’ set to hit theaters this December, Downey’s account of the shoot offers a rare glimpse into just how physically demanding bringing Marvel’s next major villain to life turned out to be behind the scenes. Between the heat, the heavy costuming, and Downey’s own competitive drive to keep pace with the rest of the cast, the production sounds like it tested everyone involved in ways audiences won’t necessarily see on screen.

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