LOS ANGELES -- If you aren't watching closely, it's easy to miss some of the work done by Tom Hanks and Halle Berry in "Cloud Atlas."

Each of the Oscar-winning actors plays six roles set in a half-dozen time periods across a 500-year span: Hanks' roles ranging from a money-crazed doctor to a post-apocalyptic father and Berry's an enslaved 19th century tribeswoman to a space traveler.

As for the demands of playing such a diversity of characters, Hanks laughingly says that they were all hard to do. Berry's answer is a bit more serious.

"It was the most fun. I got to play a white, Jewish-German woman in 1930. When would I get to do that? We had these makeup tests that might seem to go on and on, but when you're an actor, that's the fun of it -- to create something you've never done before," Berry says. "I'll never get to play an Asian man again."

Instead of hiring more actors, filmmakers Andy and Lana Wachowski and Tom Tykwer opted to have the main actors play multiple roles as a way of reinforcing the story's points about reincarnation.

Playing the multiple roles was the sinew for the contention that everything we do has an affect on other generations.

Despite having to play six characters in six very diverse story lines set in six unusual locations and times, neither Hanks nor Berry ever felt like they were making more than one movie during filming.

"It wasn't hugely different from making a movie that shoots in six very distinctive locations," Hanks says. "We did play six different roles, but they were all thoroughly prepped and researched. It sounds like this very intimidating -- almost impossible to keep track of -- process, but they knew exactly what they were doing and we knew exactly what we were shooting."

They knew, but sometimes not until the night before, which character would be needed the next day. That meant late hours trying to prepare for the role. It was a rewarding experience in the end, but Hanks said that he had a few concerns along the way.

"I never go home thinking 'Man, I crushed it today.' I always go home and say, 'Did I make any sense out of what I was doing today?' You have to trust the process, trust the alliance you have," Hanks says. "We felt like we were a cog in a magnificent repertory company and as long as we followed our instincts and disciplines, everything would be OK."

Taking on numerous roles in a film is nothing new for Hanks, who portrayed six characters in "Polar Express." The big difference was that in the Christmas film, Hanks worked in front of a gray screen and all of the characters' clothes and features were added via the computer. "Cloud Atlas" required the actors to spend hundreds of hours in makeup chairs becoming the various characters.

Hanks and Berry spent the most time together in the plot line that unfolds far in the future where Hanks' character lives in a post-apocalyptic world absent of all technology. He becomes the reluctant guide for a mysterious traveler (Berry) who needs to go to a sacred place.

This future world comes with a language that's based in English but has been modified over the centuries by regional dialects and street slang. Work on creating this future dialect started four months before filming.

"We just played and experimented until we got to something that was going to represent the next evolution of language and yet be recognizable enough," Hanks says.

Dealing with the new language wasn't the hardest part of the filming. Berry broke her foot two days into filming and schedules had to be adjusted to shoot around her injury.

The complications from her injury didn't stop Berry from fully appreciating the magnitude of the work she did for "Cloud Atlas." She doesn't expect another movie that would challenge her in so many ways to come along again in her lifetime.

"It's going to take someone to be wildly visionary and willing to take the risk," Berry says. "This film -- $100 million -- was all independently raised money. That's no small feat. I'm not saying that it can't be done again, but I don't know if the lottery will put my name in another venture like this."