The Departed is actually an adaptation of a 2002 Hong Kong cop film called Infernal Affairs. Actor/producer Brad Pitt was so impressed with this flick that he got together with Warner Bros. through producer Brad Grey to buy the rights to make an American version of the movie back in 2003.

Warner Bros., of course, was no stranger to gritty cop flicks, since they also made classic police movies like Lethal Weapon 1, Lethal Weapon 2, Lethal Weapon 3, and (yup) Lethal Weapon 4. Aside from The Departed, 2006 was a good year for the production company in general, as they would also make classic movies like The Prestige, Flags of Our Fathers, Blood Diamond, and Letters from Iwo Jima.

Originally, producer Brad Pitt was going to play the role of Colin Sullivan in this movie. But he felt he was too old to do the role justice, so he recommended Matt Damon instead. For starters, Damon had already proven he could play a kid from South Boston after his amazing performance in Good Will Hunting back in 1997. The guy was also a well-established actor in general, and like basically all the other choices with this movie, this one turned out to be good.