Joss Whedon should have appeared enthusiastic. Many others did. A portion of Hollywood Boulevard was shut down Monday evening for the premiere of Whedon's "Avengers: Age of Ultron," as hordes of whooping fans lined the street. Shiny motorcycles from the movie had been rolled onto the red carpet. Madame Tussauds even brought over some slightly ominous-looking wax figures of Thor, Captain America and Robert Downey Jr. for photo ops.
Instead, the director seemed as much relieved as happy. After helming the first two "Avengers" installments, Whedon has opted not to return for the next movie, as Marvel this month announced that Russo Bros. had been hired for the next two films.
"It's a break or a breakdown," Whedon said on the carpet, perhaps only half-joking, about his decision not to come back. "I need to see who I am when I'm not working, because I have no idea."
Unlike the cast of the "Avengers" -- which includes Mark Ruffalo, Chris Evans and Scarlett Johansson -- Whedon said he was unable to take time off to work on other projects between the first and second film.
"They all probably made, like, five other movies," he said. "They come in and say, 'I was here eight months ago. We're doing the same scene? Great.' It's kind of surreal for them, but it's immersive for me."
Chris Hemsworth said that playing Thor in the Marvel universe has allowed him to "have more choice in navigating [his] career." And without those breaks to work on other films, he said, he doesn't know if he'd be able to bring new dimension to the muscle-bound character.
"By the end of each film, you go 'Now I understand it,' and then by the next one, six months later, you go 'Why did I do it like that?' And you get another shot at it," the actor said at the premiere. "You just try different things each time, and this time I wanted to make Thor more fun and less serious -- less kingly and godly."
Mark Ruffalo, who plays the Hulk in the "Avengers" but has yet to have his own standalone film like "Thor," said he also feels there's much left for him to mine within the Marvel universe.
"It's been interesting to keep finding different places in this character. I haven't even cracked the surface yet," said Ruffalo, with his wife, Sunrise Coigney, by his side. "I don't feel locked into [the franchise]. It's good, solid work."
Which isn't to say it's always easy. With so many characters and plot lines, some in the cast said it can become difficult to keep things straight on set. Elizabeth Olsen -- new to "Ultron" as the Scarlet Witch -- admitted she sometimes had trouble staying "focused when they're always rewriting a scene and you find out something has changed." And Paul Bettany -- the intelligent android Vision -- said the multitude of cameras on set could prove confusing.
"The crew is moving so quickly, you're getting two or three takes at most," said Bettany. "There's a lot of cameras. It is hard to focus. I go around and ask what lens is on me so I know where I am in the room because there's so much going on."
So how will the Russos adjust to that kind of environment? Whedon said he isn't worried about the transition, judging by their work on the second "Captain America" film.
"They didn't need much shepherding there," the filmmaker said. "I would love to sit down with them at a drop of a hat to tell them what monsters -- uh, movie stars -- they're about to work with. There are certain things about having a giant ensemble where everybody does come and go and it's not anybody's movie. But I'm not worried about the brothers."