Upon being temporarily written out of the series after the 1978 - 1979 season, it was established Fred sold the music store and went on the road as a classical conductor with Cora tagging along. There are several post-1979 scenes where the music store set is visible in the background and scenes filmed on it.
In a scene depicting the first table read for the second season two part premiere episode "Mork in Wonderland," Gina Hecht and Jay Thomas are seen sitting down to read the script with the rest of the cast, but their characters of Jean and Remo DaVinci weren't introduced until the third episode of season two, "Stark Raving Mork."
In a scene set in 1982, Pam Dawber is shown to already be in a relationship with Mark Harmon. Dawber and Harmon, who married in 1987, didn't meet until 1985 when Gina Hecht introduced them to each other.
In a scene at the music store of Mindy McConnell's dad, there is a record rack near the front door. In the front right hand corner of the rack is Lionel Richie's 1982 solo debut LP. This album did not come out until late summer/early fall of 1982, the series' last episode aired in May of '82.
The show takes place in the late-'70s and early-'80s, but Robin throws a series 1996 $100 bill in the hat of the panhandler doing an imitation of him.