The Cheers gang goes to Gary's Olde Town Tavern during the daytime but the exterior shot shows it is dark outside.
When Carla pulls the fire alarm at the Olde Town Tavern, it activates the fire sprinklers. Automatic sprinklers are triggered by heat and wouldn't even be connected to the alarm.
John Kerry, current US Secretary of State, appears briefly, as himself. In a minor goof, in the credits he is listed as "Senator John Kerrey" (error being the second "e" in his surname).
Sam, Carla, Woody, Norm, and Cliff go to Gary's Olde Town Tavern leaving only Rebecca, who is tied up with personal business. This leaves Cheers unattended even though it is open for business and full of customers.