From a reader named Eric Geyer:
I was listening to one of your first podcasts, "The Dangers of Safety." In the podcast, you say "There hasn’t been a single on-field death in the NFL."
This isn't completely true -- there has been one, I remember it from when I was a kid. A player for the Detroit Lions named Chuck Hughes collapsed and died in the field in 1971. This doesn't invalidate your point from the story -- his death was not related to a football injury, but was caused by a heart attack.
Anyway, in case no other overzealous pedant hadn't pointed this out, I thought you would like to know :)