• Director Joss Whedon (2nd from R) and cast members Samuel L. Jackson (L), Tom Hiddleston and Chris Evans (R) pose with their awards for movie of the year for "The Avengers" at the 2013 MTV Movie Awards in Culver City, California April 14, 2013. REUTERS/Ph

Director Joss Whedon (2nd from R) and cast members Samuel L. Jackson (L), Tom Hiddleston and Chris Evans (R) pose with their awards for movie of the year for "The Avengers" at the 2013 MTV Movie Awards in Culver City, California April 14, 2013. REUTERS/Ph (Photo : REUTERS/Phil McCarten )

Fans were recently treated to the third trailer of the highly anticipated "Avengers: Age of Ultron." And now, the director of the movie Joss Whedon is revealing the details from the film.

Describing his experience of filming the sequel to a fan-favourite superhero series, Joss Whedon said that it was a "nightmare" for him.  Chatting with SFX (via The Hollywood Reporter), Joss Whedon said introducing the new superheroes, including Scarlet Witch, Quicksilver and The Vision, alongside the enormously popular Iron Man, Captain America, The Hulk and others was "the hardest juggling act I have ever, ever tried to pull off."

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The expanding cast of the movie and making everyone look like they belong in one universe seemed to be the biggest challenge for the director. According to the director, each character is unique in his/her own way. He admitted that he had never done anything like this before.

He further talked about shooting style of the movie and elaborated on The Hulk's role. Fans can expect to see Mark Ruffalo's character in a larger role in "Avengers: Age of Ultron." The director said that he wished to show The Hulk as a character and not like special effects. He disclosed that they filmed the movie in a very different manner-a bit of a documentary fashion. "I was running a lot of cameras, I was shooting long lenses, which I don't usually do," Joss Whedon explained.

The director seemed very excited about The Hulk's part. Elaborating on the green-skinned superhero, Joss Whedon said: "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."

The new trailer for "Avengers: Age of Ultron" was unveiled on March 4, 2015. It gives the first glimpse of The Vision and detailed look at the supervillain Ultron and other superheroes. Scroll down to watch the trailer.

"Avengers: Age of Ultron" is scheduled to open in UK theatres on April 23 and US cinemas on May 1.