After a ship is shot down on a remote desert planet, the surviving Marine’s only hope of survival, and getting off the planet, is in a nearby mining town which is being torn apart by two feuding gangs.

"I intend to make use of some worldbuilding?real estate that I already have."

By this do you mean that you have other works set in the same universe? Because at first I was thinking that you mean that you had land you owned where you could film. (I guess my brain skipped over the "worldbuilding" part.)
Also, yeah, many TV shows are filmed in Vancouver because it costs less. Besides, as the writer(unless you have another role as well) you don't have worry about that stuff much. That's what other people have their jobs for, to make the film the cheapest possible, and good. (can't have fast as well).The only thing you have to worry about is not be new writer pitching a multi million dollar budget film. This, even though it's SciFi, doesn't sound like that in the least bit.

There's the worldbuilding thing like Dkpough1 said, and I intend to make use of some worldbuilding?real estate that I already have.

"Putting on it another planet (Mars or whatever) raises all kinds of exposition issues. ?I still don't understand what's the dramatic point of putting the conflict on a remote planet."
It's sci-fi, so he wants it to be on different planet. Depending on what kind of terrain it is, it would be a simple thing to film it without CGI, like if it were a jungle or something. I understand that you think it will probably be something that increases production costs, but he hasn't specified what the planet is like, and I don't see much point in trying to stifle the sci-fi element he is pursuing. What's the point of even having the ships and whatever other tech, then? May as well just be a regular action movie.
Like I said, I understand what you're getting at, but in sci-fi, and in fantasy, world building is most of the fun. Star Wars wouldn't be the same if it were on Earth. The same goes for Firefly.
Personally, I don't think every piece of world building needs to have a dramatic point to the story. It shouldn't distract and such, but I think it is okay to build a world that the plot doesn't depend on, necessarily. Does Star Wars actually need to explore multiple planets and species? No. But it does.
That's just my two cents.