Hall of Fame show (Roaf in, Shields out)

[Rain Man]

Did you hear Jack Butler? He played in the 50s, and he said that when he played, a player who went down could get back up and run as long as the play hadn't been blown dead. I've never heard that before.

I guess 99 percent of the time the whistle would be blown pretty much immediately, but it's still odd. Were there times when the ref didn't pay attention back in the 50s? Why would the whistle not be blown immediately?