I love, LOVED Rex vs. Ray battle, it's as if he knew I wanted it.
Also, I thought it was hilarious that if you didn't have rumble activated on your PS3 controller, the fight with Screaming Mantis/Psycho Mantis it did a hilarious cutscene about no rumble.
Out of all the Blu-ray features the one I love the most is actually the fact that you can access the menu at any point without interrupting the movie! It may seem miniscule but I've noticed I actually check the menu more often and I've found that I usually view more of the bonus features now.