The CG cylinders were used in the movie likely because for every one person who knows that a CRT can be dangerous if mishandled there are countless thousands that know that gas cylinders can be dangerous if mishandled.

This is a rather elite subject--relatively speaking.

I'm impressed that this managed to turn into a fairly well visited discussion. I'm feeling much better now, btw.

Mythbusters has done some really cool stuff-I really liked how they worked out an elegant solution for their 'pole vault drive shaft' myth-where a car travelling at 25 mph has to drop its drive shaft into a small divot in the pavement at precisely the right moment to achieve the pole-vault effect.

I'm gonna have to look up the crystal radio one, though-I can't believe that with all of their research staff and the fact that these guys probably all grew up tinkering with stuff had never handled a crystal radio...I had two as a kid, and both worked fine!