When the Starcar lands for the second time, there is a shot where the car comes to a stop in front of the camera. In this shot, the wooden rafters of the sound stage can be seen. (Noted in the director's commentary).
In the scene where Alex first meets Centari and climbs into the Starcar, notice how Alex's hair looks natural as he stands outside the car. After he gets in and asks "What are you doing?", notice how his hair looks totally different, almost as if it is burnt or something. The actor had become very ill and had to shoot certain scenes after he got sick. He wore a wig, which explains why during certain parts of the film, he looks pale and his hair looks burnt. You can also notice the wig in the scene when the "Beta" unit rides in a truck and laughs his head off to have a good time.