Ryan Rynolds Character probably makes the biggest mistake, which was to break the quarintine, which he did only in an act of valor to save the black British scientist.
The black scientist made that initial "mistake", which had he not attempted to correct might have kept them alive, assuming they kept it in space, but of course the whole mission was to try and establish life.
When he attempts to stimulate activity with the electricity, it leads to the fall out. I had a thought that perhaps, he triggered a defensive response in the organism, but given the clear and vast intelligence of the creature, it had to conceivably have some type of rational consciousness, so its improbable that it would have kept it's rampage up if it had any other intention then consuming all life in its path.
The Japanese scientist, if I understand the situation correctly was trying to stop the "rescue" crew from boarding the ship, he wasn't trying to run for his life, he had the impression that they were being boarded, and was attempting to protect them/stop them from taking the life form back with them (even though as it turns out that ship was a fall over plan to eject the life form back into deep space.
There really was no combating the organism, it was so smart, in fact it seemed as though it was reading their minds , seeing as it was literally operating within the same thought process that the crew was at certain times.
Maybe if both crew members attempted to lure it to the escape pod together they could attempt to navigate it away, but I have no reason to believe it couldn't have over powered them both, and it was so smart, that I wonder why it hadn't tried to figure out how to pilot the escape pod itself, however ridiculous that may seem.
