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. (00:07:20)
Numb3rs (2005)
1 factual error in Counterfeit Reality - chronological order
Starring: Judd Hirsch, David Krumholtz, Rob Morrow, Alimi Ballard
Continuity mistake: Season 2 - Episode 16 - "Protest": Near the end when the guy is threatening to drop the nitroglycerin, he drops the test-tube and it lands on a red mat. However, when the agent picks it up, there isn't a mat anywhere near the test-tube.
Charlie Eppes: Everything is numbers.
Trivia: The episode revolves around a man killing people with the same first names as the thirteen apostles (Mary Magdalene being the 13th), and killing them in a similar fashion in which the apostles died. At one point, Colby and David find a box with a mannequin's head in it. This is a reference to the film Se7en, in which seven people are killed for committing one of the seven deadly sins. The film ends with the main characters finding an actual head in a box.
Question: This question is about the mistake where a SWAT officer has a magazine backwards in his MP5. I know this would be impossible on a real weapon. But, how could it have happened in filming? Rubber cast weapon? Very badly worn prop weapon? Set armourer with a hammer and no clue?