The interior set of the Star Car does not match the exterior shots.
When Alex first meets the Beta Unit, he already appears to have Alex's facial features and hair - albeit in silhouette. However, he is later taking form with skin and facial features growing over a robotic skeleton.
When Alex is playing Starfighter the second time, in a closeup, it is shown he has over 900,000 points. Right after, in a long shot, he only has 140,000 points (might only be noticeable on DVD/BluRay).
When Grig is trying to restore power shortly after using the Death Blossom, there is a cable for a 9-volt battery attached to the circuit board in his hand. However, it does not automatically mean that it can only connect to a 9-volt battery, or that something that looks like Earth-technology must be from Earth.
At time index 1:09:47 you can see the Deputy Sheriff's star has seven points like that of California Highway Patrol but then a few scenes late the same Deputy Sheriff at time index 1:13:23 in now wearing a six point Deputy Sheriff star.
When Alex and Centauri return to Rylos the second time, and as the Star Car is about to stop, you can see the ceiling of the set reflected on the side of the Star Car.