Nasa were asked so many questions regarding the year 2012 and its various doomsday predictions, that they decided to post a Q&A, listing the biggest offenders, and in turn, showing how ridiculous the film’s plot was.
A snippet of the page

Remember the Y2K scare? It came and went without much of a whimper because of adequate planning and analysis of the situation. Impressive movie special effects aside, Dec. 21, 2012, won’t be the end of the world as we know. It will, however, be another winter solstice.

Much like Y2K, 2012 has been analyzed and the science of the end of the Earth thoroughly studied. Contrary to some of the common beliefs out there, the science behind the end of the world quickly unravels when pinned down to the 2012 timeline. Below, NASA Scientists answer several questions that we’re frequently asked regarding 2012.

The post goes on to to completely disregard all of the theories, saying “For any claims of disaster or dramatic changes in 2012, where is the science? Where is the evidence? There is none, and for all the fictional assertions, whether they are made in books, movies, documentaries or over the Internet, we cannot change that simple fact.”
Head on here for the full Q&A.
[By the way, I know the movie was just entertainment, and I never took its content as fact. Just saying it before someone gives out to me!]