Following today's extended trailer, an Avengers: Age of Ultron featurette has been released, and it goes behind the scenes of the highly-anticipated blockbuster.  It's very cool to see how the production puts together their big set pieces, and it was also neat to see some of the practical effects like real pyrotechnics going off in the background mixed with live-action stunt doubles being yanked around.  The featurette also reveals that they're shooting in more distant locations than ever before (Italy, South Africa, and Seoul), the first sequence they shot was Hulk versus Iron Man's Hulkbuster Armor, and to quote Joss Whedon, "Mass destruction: Check. Superheroes check: Check.  Beautiful locations: Check."

Hit the jump to check out the Avengers: Age of Ultron featurette.  The film opens in 3D on May 1, 2015 and stars Robert Downey Jr.Chris EvansScarlett JohanssonChris HemsworthMark RuffaloJeremy RennerJames SpaderElizabeth OlsenAaron Taylor-JohnsonPaul BettanyDon CheadleAndy Serkis and Samuel L. Jackson.

Via /Film.

Here’s the official synopsis for Avengers: Age of Ultron:

Marvel Studios presents “Avengers: Age of Ultron,” the epic follow-up to the biggest Super Hero movie of all time. When Tony Stark tries to jumpstart a dormant peacekeeping program, things go awry and Earth’s Mightiest Heroes, including Iron Man, Captain America, Thor, The Incredible Hulk, Black Widow and Hawkeye, are put to the ultimate test as the fate of the planet hangs in the balance. As the villainous Ultron emerges, it is up to The Avengers to stop him from enacting his terrible plans, and soon uneasy alliances and unexpected action pave the way for an epic and unique global adventure.

Marvel’s “Avengers: Age of Ultron” stars Robert Downey Jr., who returns as Iron Man, along with Chris Evans as Captain America, Chris Hemsworth as Thor and Mark Ruffalo as The Hulk.  Together with Scarlett Johansson as Black Widow and Jeremy Renner as Hawkeye, and with the additional support of Samuel L. Jackson as Nick Fury and Cobie Smulders as Agent Maria Hill, the team must reassemble to defeat James Spader as Ultron, a terrifying technological villain hell-bent on human extinction. Along the way, they confront two mysterious and powerful newcomers, Wanda Maximoff, played by Elizabeth Olsen, and Pietro Maximoff, played by Aaron Taylor-Johnson, and meet an old friend in a new form when Paul Bettany becomes Vision.

Written and directed by Joss Whedon and produced by Kevin Feige, Marvel’s “Avengers: Age of Ultron” is based on the ever-popular Marvel comic book series “The Avengers,” first published in 1963. Louis D’Esposito, Alan Fine, Victoria Alonso, Jeremy Latcham, Patricia Whitcher, Stan Lee and Jon Favreau serve as executive producers. Get set for an action-packed thrill ride when The Avengers return in Marvel’s “Avengers: Age of Ultron” on May 1, 2015.

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