If I understand Firefly / Serenity, (or what I've been told by a security actor who was allegedly a "big fan" of the show and movie), the setting took place in one solar system. It sounded like the show borrowed a lot of cues from Traveller, but when it came down to it, it wasn't Traveller in the least. Bab-5 wasn't Traveller in the least, though both share some common threads in terms of ideas.
A competent DP (director of photography) can cover a multitude of sins. But most of all he and the director need to go over shot design and kibitz over the visual look and feel of the film. This trailer looks very vanilla flavored, and very much a fan effort. I would reccomend scrounging through the local media directory, call up DPs, and ask for reels (DVDs of stuff they've shot); shop around, and get prices. If the crew is in the midwest, then the guide of choice is the Variety National 411 (formerly the LA411;
http://variety411.com/us/los-angeles/ ). Also, hold off on aliens (because they cost money to makeup). Spend money on costumes and sets. Make it look professional, but not fancy.
Like the other guy said, 70's Dr. Who looks campy as anything in the visual effects department, but the setting and acting, with some competent camera work, offset everything else.