When Sam and Norm are discussing Norm's tab and Sam is flipping through a large black binder they are discussing how far back the tab goes. Sam states that it goes all the way back to when they didn't even know his name. However when Sam bought the bar back from the corporation at the beginning of the previous season he announced that as a celebration he was going to wipe out all bar tabs.
When Lilith and her mother Betty first arrive at Cheers, Betty asks Frasier where the bathroom is. As Frasier directs Betty, Lilith is standing by the front door. When the camera moves from Betty back to Frasier, Lilith is suddenly down the steps, standing next to the bar, at least 20' from where she had been.