Derelict, or not Derelict ? That is the question.

Just throwing this out there, but the trailer implies that the derelict crash is at the very end, but it does stay remarkably intact considering it does crash. The engineer who activates the chair may come later or earlier than it appears to in the trailer... The ship does stay intact during the crash. Maybe it's still airworthy and still a threat after being knocked down. If Shaw does in fact end up in the chair (based on another thread's discussions), then it's not completely impossible that it leaves the planet seen in the trailer AFTER the crash landing. There is nothing in the trailer that explains exactly WHY or WHEN the derelict shows up, or who is driving when it does. If taking the derelict out by ramming it failed to actually stop it from being the "weapon" it is supposed to be, then someone getting into a suit to pilot it elsewhere as a last-ditch effort is at least a possibility. It would certainly explain the apparently different final resting place of it from Prometheus to Alien, without needing two derelicts in the original story. Just an idea, anyway.

it'd be one giant coincidence. they both fell in identical position. photos of the filming location looks like the alien planetoid. my vote goes towards same ship.