Its sometimes said that the scenes of hands playing the piano were actually the hands of Jerry Lee Lewis himself, but actually, those hands belonged to professional pianist "Jason D. Williams". Both the filmmakers and Jason D. Williams have stated this.
Jerry Lee was (and is) called "the Killer" mostly because that's what he calls other people (for instance, in the movie, he shows his friend the pianist at Haney's Big House, his first record and exclaims "hey, killer, take a look at that" and later, after bringing the house down at the Alan Freed Paramount show, by setting his piano on fire, tells Chuck Berry to "follow that, killer.")
What follows are trivia items we now believe
are bogus. Some of them will have explanations, some will not. We just leave 'em
in for interest, really.