“Last Night” is a biting, witty comedy about the end of the world as seen through the behavior and relationships of a group of people in a big North American city. They’re all connected by the past, which they’d like to clear away, by the present, which last minute complications have messed up and also by the future, which, although shrinking to nothing, still remains the major preoccupation in the hours ahead. Nostalgia is a potential trap, as are compassion and fear. But fate awaits, which of course will upset predictions and alone decide the best way to put an end to it all.