The original screenplay was much darker. Apart from being a low-life, Hancock was supposed to be sexually frustrated because he couldn't have sex with a woman without killing her. The MPAA actually cleared a scene involving Hancock's explosive orgasm, but it was removed from the final cut because a test audience didn't find it funny. The tone was lightened considerably for a summer release aimed at a wide audience, but the MPAA gave the film an R twice before language and violence cuts resulted in a PG-13.
The original title was "Tonight, He Comes." The script, which floated around in Hollywood for over a decade, was later retitled "John Hancock", then finally retitled "Hancock".
Will Smith is a native of Philadelphia, home of the Philadelphia Eagles. The eagle on the back of Hancock's uniform is a replica of the Eagles logo from 1948 to 1995.
Will Smith is a huge fan of professional wrestling. He describes Hancock as Steve Austin, one of his favorite wrestlers, with super powers.
During Ray's first PR meeting, various Hollywood producers play the board members. The group includes Akiva Goldsman and Michael Mann, who have directed Will Smith or produced movies starring him.