Watch the Trains Go By - S4-E19
Continuity mistake: As Schultz is by the car, Hogan is behind the fire brigade equipment. When Klink calls Schultz, Hogan gets up from behind the equipment. A second later, in a closeup, he comes up from behind the equipment again.
Answer: It's a comedy, not a documentary.
stiiggy
Perhaps it was counterfeit. There are numerous episodes where they deal in counterfeit monies.