I was in a match where players were able to get through ivory tower and catch the flag no where near wher ethe flag actually was. I've heard different theories of using a sniper rifle while looking through the wall (you can look through the wall in the spot where the plasma rifle is on the small steps, facing toward the flag). I'm not a cheater by any means... flame me if you want but it's true. I have left games where team mates have cheated, it's something I don't agree with and do not feel it's part of the game. However, knowing a good amount of the glitches in the game I have found plenty of ways to defend against most of them. If anyone knows this and posts it not only could a defense be mad for it but also I do believe that when the more people know about it, the faster it gets fixed.
Also I would not recommend anyone to do this is any matchmaking as your xbl account will be deleted once bungie finds you, which isn't hard as the keep track of all games played and within that record you can find exactly where the flag was taken from. If you sign up to bungie.net and look at the game viewer you'll know what I mean. <