When Diane is confiding in Carla. Carla is placing glasses on a tray she is holding. While in the background the bar top is empty. It cuts to Diane then back to Carla and the number of glasses on the tray has reduced and now there is a full tray in the background.
When Cliff enters the bar and walks down the steps and the camera pans to him, you can see the stage's curtain behind him.