(1) Though inconclusive, some evidence suggests Soryu got involved in a short-notice ferry operation toward Truk. On 2 May seaplane tender Mizuho sank outside Tokyo Bay following submarine torpedo attack. She had been scheduled to move elements of the 23rd Air Flottilla to Truk. ULTRA intercepts and traffic placed Soryu as on tap to fill the gap. It is thus all the more interesting that on 15 May Rear Admiral Yamaguchi Tamon transferred the flag of Cardiv 2 to Hiryu; despite having preferred Soryu in recent operations. It is also significant that KdB sailed a day behind schedule; various reasons have been given, but a delay arranged to be confident of Soryu's readiness after such a sprint south could have played a role. Finally, it bears mention that some discrepancies concerning a reported change of Cardiv 2 aircraft tail codes in May also suggest some internal disruption of pre-operation planning. However, it must be strongly stressed it is no less likely this impression of Soryu ferrying to Truk was caused by Japanese communication deception measures. At the moment, the matter remains unconfirmed, and is possibly only of significance to a unit historian.
(2) Though most planes were recovered in the 0900 range, due to their long endurance and fuel, some Kates returning from Midway and search missions remained in the air as late as 1000. Kaga landed a recon one at 1005, and it appears that some Soryu planes had diverted well clear of KdB to avoid the air battle and took some time working back to their mother ship.
(3) "Aviation unit" or "Air Unit". ONI 1947 English translation mis-reads this somewhat, rendering "Air Force" But this is misleading as re-checked translation renders this as "Aviation Unit". Which refers to carrier force, not a group of planes as `air force' might suggest. The difference is subtle, but important. A follow-up message from Soryu's plane makes clear it was talking about a carrier force.
(4) To the informed eye the timing of the sinkings of the Soryu and Kaga barely ten minutes apart at dusk after explicit updates indicating were in no danger of sinking had always appeared almost unrealistically convenient. This even more so when viewed in context that the destroyers were desired for planned night action, and that Akagi's skipper radioed request to scuttle in the exact same time frame. Finally, conveniently, all known personnnel had been rescued--the only thing keeping the destroyers from leaving was the carriers still being afloat. However, it was only post-war that explicit descriptions and claims of Kaga and Soryu being scuttled - even naming the destroyer tasked - began to appear from Japanese veterans in eyewitness accounts. These unsolicited accounts fit neatly and seamlessly into the earlier evidence. This in addition to confirmation of omitted messages of Desdiv 4 strongly support such scuttlings.