Gomer mistook the gun port on the armored truck for a gas tank and started filling it with gas. There was quite a bit that went inside. It looked like Barney was getting wet but when he was locked in the truck fllying down the road you could see his pants were dry.
Doodles Weaver, who plays sign toting weirdo Regis, is the real life uncle of actress Sigourney Weaver.
The two men sitting as Opie enters the courthouse are not the same men seen in the rest of the scene...furthermore, they are wearing hats!
Although Andy explains why the gold shipment isn't being transported via the obvious route, it still seems a little much to transport gold from Denver to Kentucky through North Carolina!
When Barney takes over for the guard in the gold truck he is handed his Thompson machine gun. The Thompson machine gun and it's round magazine was the favorite weapon of TV and movie gangsters from the 1930's and 40's. The weapon also saw extensive use in World War II, though the round magazine by that time had been replaced by the more efficient spring fed rectangular magazine. At the end of the episode the weapon is left with Barney - quite a gift from the Department of Treasury!