I think my biggest problem with the episode is not the physics, but the fact that Flint was so many famous, brilliant, talented people in his lifetime. It almost seems like he was the ONLY brilliant, talented human in history. It belittles Brahms, DeVinci, et al., and kinda belittles the human race in general.
I'm trying (and failing) to think who the comic-book charcacter was... who, upon being asked how many famous people he had been, responded along the lines of: "Are you kidding? Do you know how unlikely that is? This* is the most famous I've been."
*Referring to his present life as a rich businessman. It wasn't Vandal Savage or any famous character. I think it was a one-off. It's driving me crazy.