Note (1):
It is of interest to note that Kaga's grounding damage produced communication traffic that led the Americans to believe the carrier had been damaged by a submarine torpedo attack in Lombok Strait in February. There was even mention of "three damaged planes". Since Kaga was loading planes at the time, it is possible this part was true. In any case, for some time - as late as April 30 - Pearl Harbor believed Kaga's subsequent period of drydocking was confirmation of such torpedo damage.
Note (2):
Kaga's Air action report appended to the 1st Air Fleet report ("Nagumo Report") gives the following additional details:
Over Midway: Shot down 9 Grummans, 2 bombers, and 1 float recco plane at about 0620 (0320 JST).
Results Obtained: 1 fighter and 1 B-17 strafed on the ground and destroyed; over 9 fighters, 2 bombers and 1 float recco plane shot down.
Losses: 1 in the air; 1 from AA fire; 1 person other than those on lost planes, killed.
Note (3) :
Nagumo's famous back-and-forth orders regarding the arming and mission for the second attack wave continue to generate controversy. What can be known is that at 0800 the flight decks of the four carriers were empty, as Japanese re-collection and American photographs agree on this point. They apparently remained empty with no strike aircraft spotted, apart from CAP operations until the Midway first strike wave began landing aboard at 0830 in homing operations. There is also some question when the re-arm for ship attack actually got underway. It seems safe to say it did not begin sooner than 0747-0750 when Nagumo radioed Tone Scout 4 for confirmation and the Soryu received order by blinker to begin the re-arm. Given the circumstances, it might have taken longer to actually commence in the hangars. Whether the re-arm began at 0747 or around 0800, the delay would prove fatal. From the known launching and landing operations the torpedo planes of Cardiv 1 evidently did not begin spotting till after 1010, and this is why most if not all were sitting fueled and armed in the hangars when Akagi and Kaga were struck. Kaga in particular, had been under close attack till 1000, then landed a Kate torpedo plane so up to that time had not spotted. Indications are she was starting to launch CAP fighters when struck.
Note (4):
Though most sources post-war had (following Nagumo report's stark outline) indicated Kaga sank from internal explosion, in May 1998 survivors of the Kaga participating in the Ballard expedition which found USS Yorktown claimed their carrier had in fact been scuttled by two torpedoes fired by Hagikaze. With further research and inquiries to Japanese veterans it was possible to shed further light on the matter and affirm its likely truth. In fact, several key witnesses all agreed Kaga (and Soryu for that matter) had been scuttled.
Subsequently, after further research, in “Shattered Sword” it was argued by the writer with fellow author Jon Parshall that the evidence and circumstances in fact all strongly supports the mounting claims by veterans and modern Japanese sources that Soryu and Kaga were deliberately scuttled by torpedoes at sunset to free the screen for night counter-attack operations.