This episode is actually three separate parts. When shown in it's first-run, it was aired in a full ninety minute segment.
Shelley Long appears as Diana Chambers, with a special guest credit. This is the first time and only time in the series after her final appearance in season five that she is seen in character.
The first episode of Cheers started with Sam walking from the back of the bar to the front. The final episode ends with Sam walking from the front of the bar to the back, as we says to a customer, "Sorry, we're closed!"