Hogan and the Lady Doctor - S2-E20
Revealing mistake: As the truck pulls into the laboratory yard, the buildings of the city surrounding the studio backlot are seen.
Hogan and the Lady Doctor - S2-E20
Other mistake: As Hogan and company listen to Klink's office, the lid is on the speaker, so they shouldn't have been heard or at all.
Answer: It's a comedy, not a documentary.
stiiggy
Perhaps it was counterfeit. There are numerous episodes where they deal in counterfeit monies.