In the scene where George and Cheryl have climbed out onto the roof of the cinema, a shot across the city skyline shows that there is a crescent moon. In the final shot of the film, a full moon is visible in the sky on the right hand side of the screen (it's the same night).
Moviegoers find out that they can't leave the cinema - there is no way out. But when Metropol is shown from outdoors, we can see lightened rooms through the windows. Were characters too dumb to jump out from the windows or to take down using the rope?