According to Doctor Strange himself (Benedict Cumberbatch), Josh Brolin wasn't on the set of Avengers: Infinity War as often as you might think, given his major role as the movie's main antagonist, Thanos. Instead, a motion capture stand-in was used for a lot of filming while Brolin was off portraying another popular Marvel character, Nathan Summers, aka Cable.
"Josh wasn't in there for much, he did his bit and then a lot of stuff with a lot of us and him was missing because, I guess, he was doing Deadpool 2 and I was doing Melrose and The Current War," Cumberbatch told Radio Times in an interview, which has since become unavailable on YouTube.
The actor added that this sort of stuff is common on big productions like this and that they made the best of the situation. "We made it work," he said. "It's often the case you can act with other actors anyways, in certain scenarios because of the amount of additional stuff you have to fit in with the environment or the magic or whatever it is that's coming out of your hands or your a--."
Despite all the Hollywood trickery that was used to incorporate Brolin into the film later on, Cumberbatch promises that you won't feel cheated and the ensemble nature of the project really shines through.
"I don't feel robbed of the opportunity, and there's plenty of footage showing there's definitely all of us there."