They could have watched a volcano bury an ancient Roman seaport, or seen Kevin Costner try to save the world and his marriage in three days flat. Instead, moviegoers kept going, and going back, to The LEGO Movie. According to preliminary studio estimates, the animated feature earned $31.4 million at North American theaters, or nearly the total of its three closest rivals: Costner’s 3 Days to Kill, the disaster picture Pompeii and a remake of the 1987 movie RoboCop.