Whoops, I took WAY too long to see if there was post-Con follow up on this thread!
The other two heroes at the first session were my Legacy (trapping SCUBA-gear citizens under the ripped-off top of the pyramid, and saving the Megalopolis Public Library from fiery doom in the opening scene) and Expatriette's buddy Nightmist, who phased her mist arm into the mystic energy stored in the sub and actually gave the Kraken a blast it could feel, as I recall.
"Citizens Rise" was a fantastically well-done event, the layers of plot and interweaving of the details all functioning beautifully within the setting of SotM. I look forward to playing another one, if you do indeed continue! And if the Sentinels MHP sheets end up available for all, that would also be an amazing thing. Also, hats off to you once again on the production values of everything the players could see. The GM side of the screen may have been as rough as you claim, but the players' side looked phenomianl. Congrats!