The Zombie voice is by none other than Steve Blum.
What Could Have Been: There was going to be a Spin-Off game called Saints Row: Money Shot/Saints Row: Drive-By, which would have been about an Ultor assassin named Cypher, which would have taken place between Saints Row 2 and The Third, and would have bridged a few gaps like closure for Dex, with Cypher assassinating him. The game was never made, and Money Shot was instead released as a standalone clothing and weapons pack (getting Money Shot would have allowed you to unlock the outfits).
The Kill Killbane ending was supposed to be the original Canonical Ending for the game. The Expansion Pack, "Enter The Dominatrix" would've continued the storyline based on the idea that The Boss let Shaundi and Viola die in order to kill Killbane. So had the Expansion pack been released as planned instead of Saints Row 4, both Shaundi and Gat would be dead.