If you look closely, after the first time the Cannonball drops off the mail, after the line Steve says "Sam, the Cannonball stops right there", they show the Cannonball, except the picture is reversed (the lettering on the tender is backwards, and the right side of the coach has 4 windows...normally the right side only has 3, with the other side having 4)
Bert's Barbershop has previously been established as being in Pixley, yet this episode has it in Hooterville.
When Uncle Joe is landing in the water tank, the shot from above looks like a model, rather than the real tank.
The nighttime footage of the Cannonball looks more like a model train than a real one.
Apparently the premier of the movie "Wings" (see the previous episode "Wings") was a big hit, as it's still showing at the theater (when Dr. Craig arrives via the jitney). It's still listed on the marquee, with a poster that says "2nd smash week"
Sid Melton played Alf Monroe on "Green Acres".