This season starts off with Mork "going native" and becoming very human, preferring to be called Morry, and Mindy has to call upon Orson to help Mork get back to normal. An elder arrives on Mindy's doorstep, which to Mindy's surprise, looks like a young boy. This is the episode that explains how and why Orkans live backwards so they start old and grow young. This was really interesting for me, because I missed the original airing of this series since I was only a newborn when the last episode aired. In my mind, the fact that Orkans grew backward was such a major part of the mythos that I figured it, and The Elder, were major parts of the mythos - I didn't realize it was introduced halfway through the series.
Besides The Elder, there are also some new characters in the children at Mork's day-care, Mrs. Comstock and Cathy, which helped to give the show a few more people to react to Robin Williams' zany comedic slap-stick. As far as an overall story arc is concerned, there are events that affect future episodes, but there isn't really a grand storyline in this series, besides the unusual observations by an alien, of course.
There are a couple of events in this season which affect the overall chemistry of the show. For one thing, Mork starts working at a day-care center. One episode focuses on the center being torn down and made into a parking lot, while others might revolve around individual kids from the place. The other event is Mindy going to work at a local news station. Eventually Mork has trouble adjusting to Mindy being busy all the time and that leads to the classic story device where two characters switch places.
One of my favorite episodes from Mork & Mindy: The Third Season, and one of the few I really remember from those early syndication days is "Mork Meets Robin Williams." I remember when I first watched this episode oh so long ago, trying to figure out what was so special about this Robin Williams character and why he looked so much like Mork. Anyway, this episode has Williams coming to town and Mindy trying to get an interview with him. It takes some fancy footwork from Mork, but eventually he and Mindy get some alone time with the famous comedian.
This season won't get any new followers to the classic series. On the contrary, Mork & Mindy: The Third Season is definitely for existing fans who are trying to round out their Mork & Mindy collection (or even their Mork/Happy Days/Laverne & Shirley collection). So unless you fall into that category, this might not be for you, but for those who are - while this DVD set doesn't have any special features, it is still a good purchase.