Factual error: The Secret Service agent says the bills are counterfeit because you can see the watermark under a uv light, which is completely wrong. The uv reactive strip is not a watermark, it's a plastic strip embedded between the two layers of the bill and fluoresces under uv as a security measure. In older bills, it glows blue as in the film. In newer ones, it glows yellow to orange and is on the right half of the bill. A fake bill would be the one that does not glow.