What Time Does the Balloon Go Up? - S3-E24
Continuity mistake: When the British spy is trying to get to the camp, the area around him seems fairly lit, as at dusk, after the sun just set. When he glances toward the gates, the sky is black, suggesting night (the shot of the gate is stock footage). When the shot goes back to the spy, it's dusk again.
Answer: It's a comedy, not a documentary.
stiiggy
Perhaps it was counterfeit. There are numerous episodes where they deal in counterfeit monies.