The horrific visions that open the final chapter of Alan Moore's Watchmen haunt you long afterwards. But Zack Snyder's movie tones down that imagery, and screenwriter David Hayter says it's because of 9/11. Spoilers below.

As you probably already know, there's no giant squid at the end of Snyder's movie adaptation. But that's not the only thing that's missing. The film leaves out the gut-wrenching images that fill nine pages of the graphic novel, at the start of Chapter 12

In the book, a doomsday clock dripping with the blood of massacred New Yorkers is followed by in-your-face carnage. There are no words, just page after page of silent faces frozen in despair. Bodies are piled on top of bodies, hunched over street corners and splayed outside of windows. If you're familiar with the book, you know that the world, for New Yorkers, has just ended. The visually arresting images push forward the final issue that the entire novel hinges upon: Is it okay to kill millions to save billions? It's violent and necessary... but it's not in the movie.