Other mistake: In the movie, as the jeep comes up to Byron Buckles' plane, the jeep rolls through previous tracks from previous takes.
Continuity mistake: The bridge Buckles and the boys put TNT on is significantly different than the one blown up. Also, the one destroyed is a re-used shot of a bridge being blown up.
Other mistake: As Buckles holds up the scale model of the Bismarck, the diagonal cut where it's supposed to "break" is visible.
Answer: It's a comedy, not a documentary.
stiiggy
Perhaps it was counterfeit. There are numerous episodes where they deal in counterfeit monies.