Hollywood hands
I always look at the hands first. It usually makes the ET laughable when it's obvious the alien technology that got them here couldn't be crafted by claws, suction cups or needles. Seems to me in order to build a civilization capable of leaving their planet, they're going to have to have hands.
As far as 'Alien Planet' goes, it was the flying Skewers I found hardest to accept. To carry their prey vertically like they did, I think they would have to have after-burners.