When I was very young (almost 20 years ago) my father was really big into sci-fi movies. I recall one that I watched, forgive me if the details are off but: The movie centered on a plot of people going to another planet (totally original idea right? ).... And, much shock to the viewer of the movie, the locals of this planet weren't exactly all that friendly. I recall some kind of ray gun that would shoot a person and turn them into a monster (in a very pod people-esqe sort of way) of some sort, or if you shot them with it a second time it would kill them. The other thing I recall about the movie, was that it had an inconclusive ending. It ends with the survivors leaving the planet and the main character realizes that the other survivors have been changed into "pod people" (doing the bidding of the hostile aliens) and heading to Earth. The main character is last seen attempting to destroy some sort of device on the ship from my memory the action was with the intent to crash the ship and prevent them from spreading whatever malicious design on Earth. I cannot remember if this movie was black and white or color unfortunately. But I am leaning towards it being black and white or very early on in the color era. Any help identifying this movie would be appreciated. Thanks!