But I would say that if it were a bomb then either A. It wouldn't go off and there'd be a slight delay between the wing tanks (I'm assuming that's what the flames are) exploding and the bomb initially punching through or B. The bomb WOULD go off in which case that plane would be in pieces, a bomb that size would have turned it to shrapnel not just the one big hole (which is still obviously catastrophic). Also, I don't see the shadow you meant (not saying it isn't there just saying I don't see it, and besides depending on where the light is the shadow of other objects/bombs could still pass along the plane. Third, from my admittedly little knowledge it SEEMS like there's a puff of black smoke and debris coming UP from under the wing in the first frame of the explosion right before the flames get out of control, if it was a bomb that burst of debris would logically be going downwards yes? In fact seems to me like the characteristic puff of black smoke is in fact there the moment before flames engulf the plane. Lastly the other bombs in frame are all passing to the right rear quarter of the plane and all seem very tightly grouped, if anything seems like a bomb would hit the right wing. Not impossible, but the farther you get from where the majority of the objects are the less likely it is to get another object from the same source going there. Not trying to implicitly say you're wrong or anything, that's just how I see it when I look at it. My gif editing skills are nonexistent so if you or someone else could freeze the very last frame that may show which way the debris is pointing out of the wing.

Well it depends alot on what type of bomb it is, if it's a bunker-buster then yes it owuld have a delay, but others had instantaneous triggers and even more had altitude or even time-based detonation and if it's either of those then the bomb wouldn't have gone off at all. I mean that's a rather small explosion for even a 100lb. bomb which was the B-24's smallest standard bomb type and THIS: www.youtube.com/watch?v=wJuoXRQAqnE is according to the video (which of course could be wrong) a 100lb. bomb detonation so if it IS a bomb then I think it would have almost HAD to tear through the wing without exploding and the result we see is just the fuel in the tanks igniting. I still personally view it as Japanese AAA but like I said, I could be wrong.