Historical references in this episode are taken from different time periods - Mata Hari, Manfred von Richthofen, and Kaiser Wilhelm were all actual individuals from World War I (1914-1918). However, the Charleston dance wasn't created until the 1920's and the CIA was established in 1947.
Bad continuity - In one of the early episodes of the series, Barney and Fred were said to have fought in Stone World War I.
Mata Harrock: (Tied up) I will tell you nothing! I will never betray my country!
Von Rickenrock: But what is your country?
Mata Harrock: Well, let's see...the Americans hired me to spy against the Germans, who hired me to spy against the French, who hired me to spy against the Spaniards, who hired me to spy against...umm...it doesn't matter! I am LOYAL!
(About a Rhinosaurus head)
Fred: Grandpa's very proud of this head. It's a Flintstone family tradition.
Barney: Yeah. Hey, you know something? I can see the resemblance.
Fred: Oh, very funny, very funny.
Barney: I was only kidding, Fred. You don't look anything like that Rhinosaurus.
Fred: You bet I don't.
Barney: Right. You outweigh him by 20 pounds easy!
This episode was recorded on 10-07-65.