My information about 30 seconds Over Tokyo is that when it was made - 1944! - the material was still not greenlighted to be used (remember, the Japanese had taken many of the Raiders prisoners, and the American public was quite upset about executions), and quite cleverly, Mervin LeRoy was going for a "newsreel-look" in these scenes. But that's just what I read somewhere.
But interesting enough, our old friend John Ford was aboard that ship - for the OSS - and when his Navy friends heard he just won the Oscar for How Green Was My Valley when they were at sea, they had a special flag made for him - with an Oscar on it. The flag was up when Doolittle started that day.