Cliff tells Norm in season three that his father abandoned the family a couple of years ago. The backstory changes to Cliff Sr. not having seen his son for at least 25 years.
Cliff's father calls Cliff at the bar and Cliff hangs up on him. The father soon comes into the bar and says he was told Cliff hangs out there, an odd thing to say having just spoke with him. Sam, who knows Cliff just spoke with his father tells him Cliff is away on business.
In the final scene, the front edge of the stage and a studio usher can be seen behind Cliff as two extras walk off the set.