Yes. It's right there on the far right of the first picture, and not there in the next picture. Flip rapidly between the two and it's OBVIOUS. As long reported, the plane actually hit the ground just in front of the building first, sliding/smearing a hundred feet or so before actually impacting the building.
1. ... How can a Boeing 757-200 – weighing nearly 100 tons and traveling at a minimum speed of 250 miles an hour – only have damaged the outside of the Pentagon?
Easy: the impact is comparable to throwing a water balloon at someone's feet. The water balloon may weigh a pound or two - equivalent to about 1% of the target's weight - but the balloon quickly bursts and the water spreads. Likewise behavior of a 100 ton airplane hitting a 10,000 ton kevlar-wrapped steel-reinforced multi-layer hardened-concrete wall: the fragile skin of the plane (just 1/8th-inch aluminum) bursts and fuel (most of the weight) spreads rapidly. That the plane actually hit the ground first (a glancing blow a hundred feet or so away) means disintegration was well underway before reaching the wall.
2. ... How can a plane 44.7 feet high, over 155 feet long, with a wingspan of almost 125 feet and a cockpit almost 12 feet high, crash into just the ground floor of this building?
As repeated above, the plane obliquely impacted the ground first, smushing it flat, then slid into the ground floor. Again, flip between the first two security photos: the plane was very low compared to the building.
3. ... Where is the debris? Any debris! Did it all disintegrate on contact?
Like this? 
How many times must we post that picture?
4. ... What happened to the wings of the aircraft? Why isn't there any wing damage?
Again, the plane hit the ground first, disintegrating the wings (which aren't much) and releasing fuel. There's damage, just not much compared to what was caused by the fire.
5. One journalist asked: "Is there anything left of the aircraft at all?"
When a plane hits something essentially immovable (like a rock-like building, or the ground at ~90 degrees), there's not much left of the plane. This is obvious from many plane crash photos.
What did happen to the plane? Where is it?
I really want to believe there was a plane, but I've never seen a plane crash with no wreckage. Where is it?
DUDE! IT CRASHED INTO THE PENTAGON WITH A FULL LOAD OF FUEL AND BURNED! That doesn't leave much left, and yes there were pieces lying around. If we fling you into a brick wall at 100 MPH, there won't be much left either; there isn't much difference.