Earlier this week, Avengers: Age of Ultron director Joss Whedon revealed on his Twitter page that principal photography has wrapped on the Marvel Phase Two sequel, with a photo that also asked, "What the hell do I do now?" One answer is, obviously, post-production, but another may be reshoots.

While reshoots are often given a negative stigma, since they imply something went wrong with the production that needs to be fixed, Marvel Studios president Kevin Feige revealed that reshoots are an important process for all Marvel movies, and that reading JW Rinzler's Making of Star Wars books made him feel more comfortable about Marvel's process.

"I'm reading the part in Jedi where George (Lucas) is finding the movie in the cut. It happened in Empire, and it happened in Star Wars. You've heard about those famous early screenings where people were like, 'Poor George. His career is over.' That brings great solace to me when we screen our movies for the first time and they're terrible and they're a big mess. I remind myself to get calm and proceed. Post is my favorite part, because it's easiest to find what's wrong with the movie when you're watching the movie."

The producer added that Marvel already has the Avengers: Age of Ultron cast members locked in for additional shooting, while adding how invaluable the reshoots are to the finished product.

"We always build in two weeks because the hardest thing about the additional photography is the actors' schedules, wrangling the actors. So we just build it in. We've done some movies that have three days of reshoots, some that have fifteen days, twenty days if not more. Sometimes we know what we need by that point and sometimes we're wrangling them anyway. There's a shot in Thor: The Dark World we call the Three Continent shot. It's one shot, with three different actors in it, that was done on three different continents. Additional photography is invaluable. Sometimes it's to fix something that's not working, but most of the time on our movies it's two-fold: sometimes a better or more exciting idea will come along, or more often something will come out of the movie - because it's too long or the movie is stronger without a particular beat or scene or shot, and you need connective tissue."

While it isn't known exactly when Avengers: Age of Ultron will start its reshoots, or what exactly they will be filming, they can also be used to shoot Easter Eggs and cameo appearances. The famous shawarma end credit scene in Marvel's The Avengers was shot right after the film's world premiere in Hollywood, just a few weeks before it debuted.