Another odd thing is that if you rearm your plane some of the ground targets that you have destroyed respawn. I tried it with the Japanese destroyers that can be found on the Okinawa map in the QMB. Took off with a torpedo, sank one of the two destroyers, went back home, rearmed, took off again and what did I see? There are two destroyers again.
I then tested that and switched their AAA off (to make sure I can do several runs on them without being shred to pieces). I sank one destroyer, rearmed went there again and the previously sunk destroyer was not only there again but did also fire its flak at me (remember I switched it off before). it seems the targets that you destroy with bombs or torpedoes do respawn if you rearm (though I need to test that further).
Another thing I noticed is that the same weapon dropped from a different aircraft has different results. If you take a F84 and equip it with two 1000lbs bombs then you can sink the right one of the two destroyers (the right one when you take off from the allied base in the south. Oddly enough the left one can take far more damage although it seems to be the very same kind of ship). If you take a F86 or F80 the ship won't sink even though you used the same two 1000lbs bombs on it.