I seem to remember someone saying that when Superman (http://www.imdb.com/title/tt0044231/)was first aired on television in the 1950s, that a lot of kids, perhaps hundreds, believed that putting on a cape gave them the ability to fly and many of them fell to their deaths. Does anyone remember this, and most importantly, does anyone have proof of this?

No, I don't believe it's true - it sounds apocryphal to me.