Dailies | 13-Minute ‘Man of Steel’ Featurette: Why Superman Doesn’t Wear Undies, Anymore (Video)

The new (and improved?) skin-tight Superman tights aren't just a costume, they are a Kryptonian tradition.

Superman doesn't wear the usual pair of red underwear over his signature blue tights in "Man of Steel," but it's not just because Zack Snyder thought it looked stupid.

A 13-minute behind-the-scenes featurette specifically addresses changes to the costume that Clark Kent's superhero alter ego has been wearing since first appearing in Action Comics #1 in 1938.

"The reason why his underwear is on the outside of his pants, it's a leftover from Victorian-era strongman," Snyder explains. "I probably looked at hundreds of versions with underwear. It fell by the boards because I couldn't make it consistent with the world we were creating."

See photos: 35 Star-Studded, Super Dramatic 'Man of Steel' Images of Henry Cavill and Cast

That world is Krypton. And the latest big-screen representation of the alien planet is a more technologically advanced fantasy world, similar to HBO's "Game of Thrones."

"It's kind of like chainmail to knights of medieval times," costume designer Michael Wilkinson said. "When we go to Krypton, you can see the counsel members, the soldiers — they all had the same skin suit."

Jor-El (Russell Crowe), who is Clark Kent's biological father, wears the same blue skin suit underneath the armor he's been seen wearing in a variety of promotional photos and trailers for the film.

"Sometimes you'd see it with a cape or sometimes armor would go on top of it," producer Deborah Snyder adds. "It's a really high-tech kind of fabric, which I think is a nice departure from the spandex."

Catch up on more changes Snyder and executive producer Christopher Nolan ("The Dark Knight") made to the American cultural icon for "Man of Steel," below.