"Movie sets require a lot of production personnel, prop makers and logistics people. How come none of them have ever spilled the beans?"
MONEY!
How much money would it take to silence one person? How many of those payments would be required?
And where is this money coming from. Let's say you paid 1,000,000 a year to everyone involved who knew. If only less than a 10th of people involved in Apollo got paid, not to mention however many were directly involved in faking, that's 40 BILLION dollars a YEAR, which is over twice NASA's current annual budget.
And if you say that the NASA Death Squads keep the Apollo people from talking, those Squads have to be kept on salary for 50 years, they have to be let in on the hoax so they know what the people they are monitoring are NOT supposed to be talking about, and since those Squad members now know about the Moon Hoax, other Squad members now have to watch THEM to make sure that THEY are not tempted to cash in on revealing the Moon Hoax.
And of course, THEY have to know WHY they are watching their fellow Death Squad buddies, and now THEY have to be let in on the Biggest Secret Ever, and to keep THEM silent...