Rebuttal: There were six frames showing the impact from a security camera, which were released after a FOIA request.[51] Furthermore, photographic evidence of wreckage on the scene and eyewitness accounts of plane wreckage and damage are consistent with a plane crash.[52] Essentially, the problem for no-planers is that the plane didn't just hit the outside of the Pentagon, but actually penetrated some distance into the structure, some of which even collapsed on top of the plane. Numerous witnesses saw it approach, the plane's wings took out several street lights on a nearby roadway on the way in, and plane components were scattered all over the Pentagon lawn.

Also, while inconclusive (and "personal commentary"), a photo was presented on a 9/11 truther website which claimed that the "round" debris observed possibly was not the wheel of the alleged jetliner. But it clearly was, albeit stripped of its outer edge.

Why would anyone expect a high-resolution video camera to be pointed at where the plane hit? The intrinsic improbability of such a circumstance would make it direct evidence of a conspiracy, and no self-respecting conspiracy would allow evidence of its existence to remain.

The Pentagon is a reinforced concrete building with blast-resistant windows. It was struck by an aluminum-skinned commercial aircraft that had already lost a wing before hitting the building: such an aircraft is mostly empty space, with voids in the wings for fuel and the fuselage for passengers; only the floor of the passenger compartment, the undercarriage, and the engine cores are particularly solid objects. The damage is consistent with this scenario: nobody but truthers would seriously expect a cartoony plane-shaped hole.[53]

Rebuttal from https://rationalwiki.org/wiki/9/11, which also debunks most other 9/11 truther nonsense.