Corrected entry: In the movie there is an aerial shot of what the fake town looks like, it is completely covered by a dome like structure and apparently can be seen from space, however soon after we see that a man tried to sabotage the show by parachuting into the town. There is no possible way he could have done this.
Twotall
13th May 2005
Correction: Of course there is. Inside the dome there are, as we can see, loads of mechanical devices to simulate things like weather change, light change, the sun rising and setting, etc. This equipment must be possible to access by maintenance crews, and the parachutist simply used one of their access ladders/elevators to the top, climbed to the inside of the dome and jumped.
Twotall