I'd not go so far as to say it's impossible, but it would have to be a single obscenely powerful lamp mounted on a very tall structure, or you'd get multiple shadows, diffused contours and wrong angles on the shadows. Lamps like that didn't exist in the 60s either. And to top it off, they'd have to simulate an environment they've never been to with guesswork based on far less data than we have today. They'd no doubt get details wrong.
There's also the evidence that shows it is in fact a low gravity and no atmosphere environment, like their bouncing and the flag swinging like a pendulum when nudged when it would stop moving quickly in the resistance of an atmosphere. I guess the bouncing could be explained by wires, but just to make the flag behave like that, they'd have to be in a giant vacuum chamber.
All this would take a giant amount of resources and leave a paper trail the size of a cross-country highway. There would be lots and lots of evidence outside of details in in pictures and videos.