Also important to remember: The Pentagon is a militarty HQ, hardened against attack, so it would probably have disintegrated many of the lighter parts of an aircraft, and the only penetration it would suffere would be from the densest pieces, notably the cabin floor and cockpit hardware, which is just smaller than the hole in the pentagon itself.
Note also, when you have something hit at that speed, it's going to punch, not splatter. The fire on the outside of the building is consistent with the postiiong of the fuel tanks in the airliner's wings, but not with the explosion of a missile, which would have penetrated the building and then exploded inside.
Breathe, SlowBoat, breathe.
Be aware, I also believe that men landed on the moon, and that the face on mars is a trick of light and shadow.