Two of my biggest mistakes were way back in the 1.4 days TMO I think.
First one was the battle of Midway. I had just refueled there when a report came in about the IJN fleet being off Midway, wasn't paying attention to the date so was surprised. I managed to sink two carriers and though that maybe I could catch them on the way home and in fact did with two more carriers down. Refueled at Midway and finished my assignment to Japan with good tonnage. In a big hurry to get to Pearl (high TC) to get my medals, pretty girls, etc. I hit a small island just east of midway. Didn't sink but the forward torpedo room boys weren't happy. Neither was Lockwood.
Second happened when I had put two torpedoes into a carrier, don't remember which one. I decided to go under her to shake a pesky DD and try to get another shot from the other side.
Just as I was going under her she capsized and pinned me against the flight deck and took me down with her. Found out you can't dive faster than a CV can sink.
That is just two of a long list over the years.
Magic