Some of the frames in the earthquake scene near the end originally appeared in Conquest of Space (1955), Ross Martin's film debut. In that film, the quake occurs on Mars near the end of the movie.
In the late 1800s, geologists agreed that fault lines were the incidental damage left by earthquakes. It wasn't until geologic studies prompted by the 1906 San Francisco quake that folks realized slippage at fault lines caused quakes. At the time this episode was made (the late 1960s) plate tectonics was still a new and unproven notion.
The villain of this episode is named Orkney Cadwallader. In 1878 the world's largest flour mill, in Minneapolis, Minnesota, was destroyed by a dust explosion so powerful that many residents thought an earthquake had occurred. The mill's owner was named Cadwallader C. Washburn.
This episode contains much more humor than the other ones of the entire show.