I disagree about not showing Pearl Harbor. It was important for Layton's arc (since his intelligence was being ignored, and he takes the failure personally) as well as framing the larger context. Also, as the movie focuses primarily on Bombing Six, the squadron did lose several aircraft when they arrived on a ferry flight during the middle of the raid so showing that fits into the squadron's narrative, as well. It also sets up the personal stakes for Dick since his family was in Hawaii.
I'll reiterate the problem I had with what they showed was simply that this should have either had a longer run time than two hours, or should have been a miniseries.