Uhmmm so, several times during the nebula explore missions I have recieved the mission that states some to the effect of; 'go to the old klingon battle cruiser and await further instructions.'
Now there is something highlighted in the mini mao but despite having got this mission in 3 different explore nebulas and having attempted at least 20 times over several weeks, I have yet to ever find this freaking battle ship. It's just not there.
I've run into a couple of the "go to the ship" mission that seemed to be missing a ship. I found that sometimes the ship is there, just at the top or bottom of the Z axis and not in the mid-range level where you warp in to the map. It doesn't help that this seems to happen on the darker maps which may not have a bright background helping to make the target stand out.