We reveal some of The Book of Eli's easter eggs

Denzel Washington's upcoming post-apocalyptic sci-fi movie The Book of Eli knows it's only the latest in a long, venerable line of similarly themed movies, and it actually pays homage to them with easter eggs.

Brother directors Allen and Albert Hughes slipped references to post-apocalyptic films and other classics into Eli (spoilers ahead!).

An example: When Eli (Denzel Washington) spends the night in Carnegie's (Gary Oldman) town, check the wall for a movie poster: It's from A Boy and His Dog, the 1975 apocalyptic movie that starred Don Johnson. Albert Hughes admitted the homage was not in the original screenplay.

"That was us," Albert said in an exclusive interview last month in Beverly Hills, Calif. "We put it in."

There's another wink to the famous movie in Eli, Albert added: "Also, one of the snipers on the rooftop in the shootout had the exact gun from Boy and His Dog. That's Don Johnson's gun."

There are more posters to spot, too. "I think we even had A Clockwork Orange in there," Albert said.

Screenwriter Gary Whitta said that his story was influenced by an obscure British apocalyptic movie. "When I was a kid growing up in the U.K., they made us watch this TV movie at school, a BBC film called Threads," Whitta told a group of reporters. "It's about a nuclear attack on Sheffield. It was kind of like our version of The Day After, where it was just brutal. It was just terrible, and you saw not just the immediate aftermath but how civilization would have devolved 10 years down the road."

Other non-sci-fi easter eggs include shots and motifs lifted from the '30s film noir Scarface. "In the 1932 version, every time somebody gets killed in the movie, you see an X in the frame," Albert Hughes explained. "It's either lighting on the door or something. When the Valentine's Day Massacre started, there's a beam of seven Xs in the warehouse. He goes, 'OK, up against the wall, all seven of ya.' The camera comes down, and it's the shadow of seven guys that get shot. So we took a tip from that, and every time Eli killed somebody, there's a cross over him, a religious thing in the frame or a religious number in the frame." Cool, right?

Also, look closely when Solara (Mila Kunis) searches Eli's belongings while he sleeps. "She's going through his bag, and she finds this old badge that says, 'Welcome to Kmart. My name is Eli. How can I help you?,'" Whitta revealed. "That was the idea. This was a guy who stacked shelves at the Kmart before."

The Book of Eli opens Jan. 15.

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