When Avengers: Age of Ultron hits theaters, Scarlett Johansson's baby bump won't be visible. The actress got pregnant just before filming began, which slightly complicated the production process.

(Johansson and her fiancé, French journalist Romain Dauriac, are expecting their first child together.)

"She's not going to spend the whole movie carrying groceries," director Joss Whedon, 50, says in Entertainment Weekly's double issue. "We didn't trim any scenes. We're like, 'We'll make it work.'"

The film boasts an all-star cast that includes Robert Downey Jr., Chris Evans, Chris Hemsworth, Samuel L. Jackson, Elizabeth Olsen, Jeremy Renner, Mark Ruffalo, James Spader and Aaron Taylor-Johnson. To accommodate 29-year-old Johansson's pregnancy, Whedon hired three stunt doubles for action scenes.

That's when the movie magic begins. The stand-ins wear dotted maps on their faces, which will serve as guides for visual-effects artists who will graft Johansson's face onto their bodies in post-production.