Ship collision analysis/alternate theories

After staring at the alien ship in the trailer, I just noticed something very subtle about the BIG BANG when it "collides". There seems to be another fire spewing some very black smoke from the middle of the ship before the vessel can even rotate far enough for that fire to be related to the bigger explosion. It's very hard to see it in a still picture. But when you see it in motion, the speed of the black smoke reveals something unrelated to the BIG BANG, yet that smoke does extend back to where the bigger explosion came from. When the ship is on the ground, it doesn't give away too many clues, either. The part where this other fire should of been coming from is a bit darker than the other side of the ship but can't really be confirmed as fire damage because of all the smoke in the way (generated from hitting the ground). Never the less it makes me wonder, if there was a second fire, was it internal or external? David (the you-know-what) appears to be on the alien ship at some point. And what would this suggest about his motives? Could he have caused the second fire? If this is true, it would have implications for Vicker's motives as well. Could they both have the interests of their crew at heart in stopping an evil menace? Or maybe they are both so devoted to the company, they are doing it out of greed. They want something on the alien ship (or at least Vickers does, Dave does what he's told). After David fails to bring it down, Vickers starts to panic and heads for her own ship's self destruct as the alien ship gets closer. This might explain what poor Janek is looking at with red lights in front of his face. He's watching Vickers on camera flick the switches as the ship has its coolant shut off! This would also explain why Vickers is the only one running to the escape pods and why there doesn't seem to be any real collision damage on the alien ship's arm when it hits the planet's surface. Thoughts?