Give me time to do some research (as in, rewatch From the Earth to the Moon and Apollo 13), and I'll do a column about it for the film site I write for. But the short version is, yeah, dust and movement.
Thanks! If you do, it would make interesting reading.
I suppose you could CGI the dust, though it's awfully expensive and time consuming for something only a handful of people care about.
By the time "From the Earth to the Moon" was made, CGI technology was just about capable of effects like that, although as you say, they would be very expensive and time consuming. There was nothing even vaguely up to the job at the time of Apollo.
I think I mentioned, either here or on CQ, that I spent many years working on graphics system software, and if anything remotely capable of those effects had been available in the 1960's, it wouldn't have stayed a secret for long, since the movie industry would have leapt on it (much as they did in the 1990's).
People who believe that the Apollo films, videos and photographs were faked seem to have done no research into what tools were available at the time, and apparently think Photoshop was developed in the 19th Century, probably running on Babbage's Analytical Engine...