Actor Bradley Cooper surprised an audience at the AMC Boston Common Tuesday night when he turned up at a screening of his movie “The Place Beyond the Pines.’’ The film’s director, Derek Cianfrance, was the only VIP booked for the screening. He was supposed to answer questions for an audience of members of Boston Globe Insiders (a program that holds special events for Globe subscribers). We’re told that Cooper — in town to film the new David O. Russell movie — was having dinner with Cianfrance, and the director asked him to tag along to participate in the Q&A. Apparently, some audience members tried to sneak out of the film before the Q&A with Cianfrance began. But they were told it would probably be in their best interest to sit back down. When Cooper appeared, they went wild, gasping and taking photos with their cellphones. Cooper, who sported a scruffy look, told the group he filmed “Pines’’ before “Silver Linings Playbook,’’ and that the film helped him prepare for his Oscar-nominated role. Cooper was also thanked for his performance in “Silver Linings’’ by a young man in the audience who identified himself as bipolar. Cooper should be around Boston on and off for the next two months with his costars on the Russell movie, who include his “Silver’’ costar Jennifer Lawrence, Jeremy Renner, and Christian Bale. Cooper was also spotted Tuesday night at the Four Seasons.