Just the thousands of people who were involved in the design and the launch. This was 1969 and people had a conscience back then. No way they could get away with faking it.
This is all just a part of the communist plot to destroy the significance of America heroes and achievements. You are obviously falling for it.
The contractors and subcontractors all did their jobs to the best of their ability.
They had no special insight on whether the landings were real or fake.
NASA had simulation after simulation after simulation....for the vast majority of their employees they had no way to tell a simulation from the real thing.
That was not their fault either.