People getting below 5 minute times on the timed league missions. When it's not even possible to run through those levels with no enemies that fast. It has something to do with rogues showing up, and a few people have said that the timer resets if you disconnect then reconnect.
And yeah, it's only for bragging rights. But for people who want competition that isn't direct PVP, it's a valuable thing to have in the game. And when it's based on faulty design like this, it might as well just not have had dev time wasted on it in the first place. :/