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.
Numb3rs (2005)
Episode list - season 1
Starring: Judd Hirsch, David Krumholtz, Rob Morrow, Alimi Ballard
More mistakes in Numb3rs
Amita Ramanujan: Charlie, where did you learn all this stuff about assassination?
Charlie Eppes: If I told you that I'd have to kill you.
Amita Ramanujan: Okay, seriously.
Charlie Eppes: Seriously.
Trivia: Judd Hirsch is an astro-physicist and can actually do the math Charlie does on the show. He caught the acting bug in school and chose that over physics.
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?