Those have been in there for as long as I can remember. I was helping a friend through the Campaign a couple of weeks back. When she was talking to the Queen on the Reef, I was messing around with my inventory, hit LB and noticed her location actually said "Mercury." Not sure if that's a bug, but it was interesting, because it at least means Mercury is where that cut scene is "physically" located, much like the hidden rooms in the sky box of some old FPS games that you could clip to and find the models of NPCs who were shown on a video communicator or tv.