However, now that it's 2008--a time when you can have your uterus outfitted with a tiny plasma screen so your unborn child can just watch Dora and maybe stop kicking you for five seconds--people don't have such dramatic physical reactions to film. Most of us understand that movie bullets aren't going to suddenly fly out of the screen and into our bodies as we sit there, prone, in the theater.
Still, the Motion Picture Association Of America doesn't want to take any chances, which is why they told the director of Watchmen, Zack Snyder, that he couldn't have a guy pointing a gun at the audience in the trailer. Snyder replaced the gun with a walkie-talkie. This way, if anyone from 1903 watches the trailer, instead of ducking and/or running for their life, they'll just curl up into a ball, rock back and forth, and mumble, "What world is this? What is happening to me? Where am I?"
From MTV Movies Blog: