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 script was first written by Vincent Ngo in 1996, and it languished for close to ten years. Later, the script was picked up and re-written by Vince Gilligan, to be directed by Jonathan Mostow, for a 2007 release. Gilligan wrote the second draft when Sony picked up the script in early 2005.
Peter Berg said he did this movie for his young son. While editing The Kingdom (2007), his son's frequent visits to the editing room prompted him to make a comic-book style movie. When this script emerged in 2006, with no director attached, he jumped at the chance. In the DVDs extras Michael Mann was actually going to direct the movie. He felt he wasn't the right person, due to all of the CGI sets, and suggested Peter Berg.
Daeg Faerch, who plays Michel, also played young Michael Myers in Rob Zombie's 2007 "Halloween." In one of the opening scenes, Michael Myers' mom's boyfriend insinuates that he's too feminine and says, "He's probably a queer. He's gonna grow up, end up cutting his genitals cut off, and changing his name to Michelle (Michel)."
The trivia items below may give away important plot points.
The symbol of the eagle appears to identify Hancock as the Greek god Zeus. That would make Mary Embrey Hera. According to Greek mythology, Zeus and Hera were not only husband and wife, they were also brother and sister. According to the Iliad, Zeus is stronger than all of the other gods of Olympus combined. He tells them he could dangle them all from the heights of Olympus on a rope held in one hand, but none of them could do the same to just him. Mary claims that she is stronger than Hancock, but Hancock is clearly stronger than her. For instance, he survives being shot over and over, while still being strong enough to get away from her. In the hospital, Mary says that Hancock was different from the rest of the gods, and that he was meant to be a hero.