(On the premiere episode of "Late Night with David Letterman" Dave asks Don Herbert if anyone was ever injured on the "Mr Wizard" show.)
Don "Mr Wizard" Herbert: No, not really, but because of the type of show we were doing anything could happen. Only once during an experiment where we light a candle under a glass bottle with a little coil next to the wick. And one time in rehersal we got the wick wet, so when we later set it up and turned the current on it got hotter and hotter and vaporized the candle so that in the bottle we had a mixture of vaporized parafin and oxygen and it disappeared from the close up. Sssssssswit! Up into the lights. And of course I was shocked because I thought 'my gosh the bottle blew up'. Turned out I heard the bottle clang down behind me so I knew -- and the child standing next to me was covered in water, I was too. As soon as I saw she wasn't hurt I got a towel and dried her off and dried myself off. And we went on doing it. -- And that was the only time we ever edited the show -- we cut the laughter of the crew. We could hear them laughing all the way in the control room.