The dramatization of the Enola Gay taking off is shown during daylight hours. On August 6 1945, the Enola Gay departed from Tinian on its six-hour flight to Japan at 2:45AM, several hours before sunrise.
The narrator says that the atomic bomb was dropped on Hiroshima at 9:15AM. The atomic bomb detonated over Hiroshima just past 8:15AM local time, as memorialized in multiple clocks and watches across the area. The Enola Gay flight log, using times based on their original departure from Tinian, has "Bomb Away" logged at 9:15AM.