The tapes that were confiscated generally do not show the Pentagon, but nearly all of them show some perspective of the sky. It would seem that a reason for confiscation could be an attempt to keep the thousands of individual images of the sky from being analyzed, but such a reason could be argued as legitimate protocol (one argument being that an entity could study how to successfully angle a plane at the Pentagon for an attack in the future).
All other thoughts and possibilities aside, the idea that Flight 77 itself did not hit the Pentagon can only raise questions that would need to be provided for. An attempt to create a faked flight would dramatically increase the probability for outright exposure, which would be grossly inconsistent with a critical need to minimize such exposure.
Shooting down such an object elsewhere would require the same minimization. For this reason, I would say that any argument intending to put forth that 77 didn't hit the Pentagon must be argument that includes 77 being destroyed over deep ocean--away from all land, shipping lanes, fishing areas, etc., in order to minimize exposure.
((Completely within an appropriate realm, I will say it is interesting that the reported caller from the flight, who was said to have provided a description of the situation--including a special point of stating that they were "flying over houses"--was in fact connected to the very inside of the administration.))
