well mainly that out of the 3 predator and two of them be kill easily and i mean watch them fight that one alien be like watch a 2 old child fight a lion . however the one main predator who be the big wuss ever to come from the predator home world because he have a soft spot for human and well human and kill dozen with relative ease also and in alien the acid burn through a lot of metal floor and however this woman face have develop the ability to with stand this potent acid . i therefore deduce that the woman be in fact a terminator and send back in time for a completely irrelevant mission . at least my explanation make more sense then the movie .