I was on wikipedia when I saw a link to Ernest Borgnine (voice actor of Mermaid Man), I've never seen what he looks like so I checked the page.
He looks a lot like the guy featured in the original MMBB episode in season one, where SB says something like "old people are cool," and it shows an old guy winking and giving a thumbs-up.
Is that Borgnine? It would be really funny (and witty!) if it was. I'm sure there are little elements in a lot of episodes that many of us have missed................