The footage of the decorated Cannonball is from the Petticoat Junction episode "Cannonball Christmas" (1963). That's why those scenes are in black and white.
By Christmas 1968 the Clampett fortune has now expanded to 80 million dollars.
Percy Helton's character name, Homer Cratchit, is probably an allusion to Dickens' "A Christmas Carol," though only in general terms, as he had already played the character in a prior episode that had nothing to do with the holiday.
Sam Drucker (Frank Cady) keeps a rabbit's foot and a buckeye in his lockbox/bank for insurance against being robbed. In some cultures, the foot of a rabbit is carried as an amulet believed to bring good luck. This belief is held by individuals in a great number of places around the world, including Europe, China, Africa, and North and South America. A buckeye is a seed about the size of a walnut from a "Buckeye tree." According to folklore, the Buckeye resembles the eye of a deer and carrying one brings good luck.
This takes place in December 1968.