I don't think they were even trying to make it look serious. It's based on a video game anwyay, right? This is why i don't want them to make a Halo movie.
"â€¦when a calendar comes to the end of a cycle, it just rolls over into the next cycle. In our Western society, every year 31 December is followed, not by the End of the World, but by 1 January. So 18.104.22.168.0 in the Mayan calendar will be followed by 0.0.0.0.1 - or good-ol' 22 December 2012, with only a few shopping days left to Christmas." - Excerpt from Dr Karl's "Great Moments in Science".