Although I believe the possibility of Angel being the Rat is extremely low, I just want to play the devil's advocate. Angel could have easily tripped the "Alarm" from within the room and pretend to go to Burt's Armory. Knowing Hope can't see a thing, he could have easily made it sound like he was leaving, but re-enter the room and shoot Pippen. I have always thought that Angel was insecure about always being in Michael's shadow...could drive some people insane. Just throwing this out there.

Do I believe Angel is the rat? No, but I could be wrong. I cannot even come close to comprehending the genius that is KC... =)

Please don't flame me