The last time Burt Mustin appeared as Grampa Jensen, in the 5th season episode The Barber Shop Quartet his last name was spelled Jenson.
Owen Bush is credited as "Chauffer", which is actually the wrong spelling. It's spelled correctly in the guest list for this episode.
Uncle Joe says he hasn't fouled things up this bad since he ran the Cannonball into the Pixley depot. That happened on the 4th season episode "The Rise and Fall of a Tycoon"
Betty Jo mentions she was the one who found Dog and brought him home. This happened in the first episode of the 2nd season "Betty Jo's Dog"
At the beginning, when Dog is chasing the train, the footage is the same footage used on the closing credits, although it's a bit longer.
A close-up of Steve and Betty Jo's marriage certificate is shown in this episode, and shows the date as June 7, 1967.
Burt Mustin plays Grandpa in this episode, although it's not specifically stated whether he is Grandpa Miller, or Grandpa Jenson (as he appeared in several other episodes). A mention is made of Grandpa Miller getting the coffee and doughnuts though. He plays the same exact role as Grandpa Miller, complete with hard of hearing and playing the cymbals in the Hooterville Volunteer Firefighter Band.
A reference is made to Uncle Joe not being able to stop the Cannonball and running into the Pixley depot. This happened on the 4th season episode "The Rise and Fall of a Tycoon"
A big deal is made by Steve over his falling for Betty Jo when he was supposedly "going steady" with Billie Jo. He hasn't dated Billie Jo since "The Eternal Rectangle", and it was reiterated that they were just friends now in "It's Not Easy To Be A Mother". Most likely, this episode was scripted before those, and corrections weren't made nor noticed during filming.
Editors reply: He fell for Betty Joe (and she fell for him) in the previously aired episode "You Know I Can't Hear You When the Thunder is Clapping" after they landed the plane in the thunderstorm.
Rufe Davis (Floyd) gets to show off his talent for doing sound effects on this episode, at the party.