There were a lot of surprises in Avengers: Endgame, and we don't just mean in terms of plot twists. The movie had some other elements that were genuinely shocking for fans of the Marvel Cinematic Universe, including Captain America's language. The notoriously proper superhero's vocabulary branched out to quite a bit more swearing than fans were used to hearing from the First Avenger and now we know why.

In the commentary track available on the digital release of Avengers: Endgame, director Joe Russo and film co-writer Stephen McFeely explained that yes, Captain Americais swearing more, but there's a pretty solid and understandable reason for it.

"You notice, this 2023 Cap swears a lot more than the old Cap," Russo noted. It turns out it was something McFeely didn't notice on set.

"Yeah, I noticed this," McFeely said. "I didn't remember it on set."

"I mean, this guy's been through a lot," Russo explained.

Saying that Captain America has been through a lot is kind of an understatement, and a big one at that. He went from not being a fit specimen for the Army to being a super soldier, to seeing his best friend die in front of him, to saving the world from Hydra at the cost of his own life. Then, turns out he didn't die and was just frozen and comes back 70 years later, the woman he loves has lived a life without him, the world's changed, and in the course of being a hero once again he also finds out that his best friend didn't die but was turned into a killing machine for the very bad guys he saved the world from back in 1945.

That's a lot. And it's only the tip of the iceberg when it comes to a post Snap world. Not only has Captain America long many people he cared a great deal about in the snap, but he's also continuing to shoulder a lot of the weight of trying to help the world move on. From a psychological perspective, it's an awful lot of trauma for one man to bear so the increased use of swearing makes a lot of sense . It also opens the door for one of the most hilarious moments in the film, the "America's ass" scene that turns out was fairly controversial even among the directors and writers.

“And here we are looking at the backside of a famous scene from Avengers,” Russo says.

“Speaking of backsides, there's America's backside,” Christopher Markus adds as Cap’s ass appears onscreen.

“A completely different perspective. And then probably the most controversial joke in the whole movie, ‘America's ass.’ Controversial for all of us. That was hotly debated,” Joe revealed.

“Was it?,” McFeely asked.

“Yes,” confirmed.

Avengers: Endgame stars Robert Downey Jr. (Iron Man), Chris Evans (Captain America), Josh Brolin (Thanos), Scarlett Johansson (Black Widow), Chris Hemsworth (Thor), Jeremy Renner (Hawkeye), Brie Larson (Captain Marvel), Danai Gurira (Okoye), Paul Rudd (Ant-Man), Karen Gillan (Nebula), Mark Ruffalo (Hulk), Don Cheadle (War Machine), Tessa Thompson (Valkyrie), and Bradley Cooper (Rocket Raccoon).

Upcoming Marvel Studios projects include Black Widow on May 1, 2020, The Falcon and The Winter Soldier in Fall 2020, The Eternals on November 6, 2020, Shang-Chi and the Legend of the Ten Rings on February 12, 2021, WandaVision in Spring 2021, Loki in Spring 2021, Doctor Strange in the Multiverse of Madness on May 7, 2021, What If…? in Summer 2021, Hawkeye in Fall 2021, and Thor: Love and Thunder on November 5, 2021.