The TV announcer mentions the Dow Stones rock market (Dow Jones stock market).
The music in the background is from the William Tell Overture, also known as Happy Anniversary.
Fred works for Slate Quarry Co.
During the episode's finale, when the spaceship lands for the second and last time, it appears to be night time. But at the same moment where Fred is chasing all of his duplicates down the street, it appears to be daylight.
This episode was recorded on 7-08-63.
Two more additions appear in the opening credit scene. On their way to the drive-in, the Flintstones are joined in their car by the Rubbles. When Dino pokes his head through the car roof at the drive-in, Pebbles and Bamm Bamm are both placed on his head side by side.