Trivia: In the gym, Carter isn't wearing his gloves. Therefore, the wedding ring that Larry Hovis wore in real life was visible. He wore the gloves because he steadfastly refused to remove it.
Trivia: Werner Klemperer (Kommandant Wilhelm Klink) was born in 1920. So here when he says to Carter, "I am 49", he's declaring his real age.
Answer: It's a comedy, not a documentary.
stiiggy
Perhaps it was counterfeit. There are numerous episodes where they deal in counterfeit monies.