Did someone (Zack Snyder) make the Watchmen movie ending different than the Watchmen comic ending? HE MIGHT HAVE. If you'd like to find out how, read this possible spoilers...
A couple of people who attended the screening posted reports on the IMDb message boards, only to have their posts quickly removed. Nothing has been officially confirmed, so PLEASE consider this with a grain of salt for now. According to the reports, the climax of the graphic novel where Veidt releases his squid in New York City, was not in the movie. Instead, Dr. Manhattan and Ozymandias build a machine that mimics Dr Manhattan’s powers and Ozy uses the machine to set off atomic bomb like explosions in various cities around the world.
Well, in fairness, removing the giant cephalopod scene worked for Goonies, so maybe this is a good move. But the same time, fanboys didn't go to Goonies expecting an exact and faithful recreation of their favorite comic of all time, so no, it's probably not a good move.