The back of the roof/cargo bit
imgur: the simple image sharer
a full back image shows STA numbers, which is the spars or ribs that go all around the "tube". So the same number can be roof or cargo bay or either wall. STA number was used for identifying the location and WSJ themselves wavered about it in different editions. The colour being white, I vote for roof.
imgur: the simple image sharer
centre image is the rest of the roof over business class, folded over on the port wall. The open section is the door in front of the wing; the section broke clean at rivet line behind the first porthole.
bottom is Missile fin???
most images of BUKs show them very green, including fins, maybe a white tip. But I found some that have shorter side fins and larger tail fins, in BARE METAL, so those strange bits of metal are possibles.