Sam comments about the Boston traffic. Throughout the 1980's, the Boston's transportation infrastructure was going through a major change to redevelop the entire downtown highway system known as "The Big Dig." It began in 1982 and was officially completed in 2007.
Sumner explains that they have reservations at Maison Robert. Maison Robert was one of the most popular restaurants in Boston for many years, bringing fine French dining to the city before, through, and after the peak of the French dining resurgence in the US. They opened in Old City Hall (just a couple of blocks from Cheers) in 1971, were an iconic spot by the time this episode aired in 1983, and it was still a popular location when it closed in 2004 due to the owner/founder/chef starting to feel his age. Founder Lucien Robert died at the age of 87 in February of 2014.
Sam pretends to read the August 1983 edition of Playboy with Sybil Danning on the cover.
Diane uncharacteristically calls Cliff Cliff instead of Clifford.