If you thought Joss Whedon had it all figured out heading into "Avengers: Age of Ultron," you'd be wrong.

"Shoot me in the face! It is a nightmare," the director quipped, speaking with U.K. magazine "SFX" and reported by THR about the anticipated Marvel Studios sequel. "They're very disparate characters. The joy of the Avengers is they really don't belong in the same room. It's not like the X-Men who are all tortured by the same thing and have similar costumes. These guys are just all over the place. And so it's tough. Honestly, this is as though as anything I've ever done, and I haven't worked this hard since I had three shows on the air."

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But despite an increased cast size, Whedon assures fans there's at least one returning Avenger who will see more screen time in the sequel than in the original. "There is more Hulk in this movie than there was in the last," he said. "[W]e went in with this mission statement, to shoot the Hulk like a character in a movie, and not like a 'Look what we've got!' We have 'overs' - blurry 'Hulk's over there! Bits, very quick shots. Everything isn't 'We built the Hulk so for god's sake you're going to watch him in this long take, full frame, the whole time!' We really got to make him one of the characters in the movie. And that was a gift."

"[W]e shot this movie very differently. I was running a lot of cameras, I was shooting long lenses, which I don't usually do."

"Avengers: Age of Ultron" opens May 1.