Sam and Gus both say that Sam has owned Cheers for 17 years. This conflicts with earlier episodes, in which Sam said he had bought Cheers more recently.
In episode #1.2 Sam's Women (1982), Coach discovered that Gus, the former owner of Cheers, had passed away. However, in this episode, Gus returns to work at the bar for one evening. Coach's source was obviously wrong about Gus.
When Gus exits Cheers, he heads right toward the dead end. He quickly turns to go the other way up the stairs.