The Herkimer Battle Jitney. The only thing missing was Flaming Carrot himself, considering the Mystery Men were originally a two-part story in issues 16-17 of the Carrot's comic book. Worth the read if you can find 'em.
Yes, they got their asses handed to them by mooks shortly after, but after Raja and Shoveler make their entrance and defeat Big Red, we knew who to root for.
Invisible Boy realising that, while he is only invisible as long as nobody (not even Invisible Boy) is looking, that might just allow him to shut down the automated killing device above the door to the secret lair.
Carmine the Bowling Ball going ape-shit on the Psychofragulator.