Ben Affleck, Christian Bale caught shopping for Batman costumes

Ben Affleck as Batman and Christian Bale as Batman.

It's a chance encounter of superhero proportions - Batman has met his Batman predecessor shopping for a Batman costume.

This was no wardrobe emergency. Ben Affleck told the crowd at Comic-Con that his son wanted to dress as Batman for Halloween. As it turns out, so did the son of former Batman Christian Bale.

Affleck's appearance at Comic-Con, which attracts 130,000 fans over five days, was his first public foray after the announcement he was splitting from wife, actress Jennifer Garner.

The Batman star looked gloomy, but scored plenty of laughs when he told the crowd how he randomly ran into Bale at a Los Angeles costume store.

Both actors were with their young sons, who wanted to go as Batman for Halloween.

"There he and I were standing in the Batman aisle," Affleck said.

Affleck did ask Bale if he had any tips on playing the superhero.

The advice sure packs a punch.

Affleck said Bale told him: "Make sure you can piss in that suit."

Oscar-nominated Australian costume designer Michael Wilkinson was responsible for creating Batman and Superman's suits.

"Yeah, we put a zipper on it," the film's director Zack Snyder added.

Batman v Superman is set for release in March next year.

- AAP