SELEN

If a film is consistent and real life like then it is film continuity. However if there are mistakes in a film then it is not film continuity because its not realistic and the audience wont feel as attached to the film as they know that the film is a film. 
After Gerry gets smacked in the face by the 'broken' suspender clasp, we see the silver clasp land under the dresser. Yet, when he's moaning and lifting his leg to get onto the bed, we can actually see the clasp still intact on the front suspender that came loose, which is dangling right behind him (just look between his legs). Of course, in the next shot, that clasp is gone. Since the silver clasp is one of the plot points, this is bizarre to say the least.