I was playing on the official servers yesterday and there I experienced something which could be considered a bug in one way, and also an extra experience of gameplay.
Part of the team, got left behind, therefore, the mission did not end. (you could argue about this being a bug, but yet..)
I was in the group that was left behind, which was also in trouble as there were firefights with the opposition. Then i hear people on voice wondering why the mission hadn't ended. Someone explained to them that half the team was still out there and that's why the mission wouldn't end.
Anyway, to make a long story short. The left behind group makes it to an LZ and manages to hold out until a chopper actually makes it in for a pick up and delivers us to base so we can end the mission.