1. I sank the entire Japanese fleet during the Leyte mission, including the Yamamoto before they could withdraw. (Yes, I am that awesome.

2. During the Okinawa scenario right after that, the Yamamoto was back again. I sank it again, no problem. Got the campaign event "Yamamote sunk, big blast and so on" again. This is not the biggest deal, but maybe you want to fix that continuity error.
Still a great game.
