The final run in toward port in Japan after Midway was tense, jittery and full of submarine alerts. However, there seems to be no record of an attack by a US sub on that particular date. Admiral English tried to organize some submarine attacks on the retreating Japanese, but it all came to naught. I think it's safe to say that after the calamity they had been through, that Yamamoto and company were a bit on edge and were seeing the enemy everywhere.

Just remember with RSRD most TF take exact paths from base, so often you can better ambush them leaving port or in a strait if you choose this style of play. For instance, you can catch the Midway carrier group coming through the Bungo heading for battle, all the capital ships in one long single line. RSRD has numerous groups for most battles, again Midway, you have several large TF, but most go for the carrier group. There is also the large invasion fleet leaving Saipan for Midway that is fun to attack. Total, they're about 5 large groups involved in the Midway battle, plus the northern groups.