Capricorn One – The 1978 Fake Mission to Mars

I saw this as a kid and really liked it, but probably didn't get the whole plot and all the politics.

There was recently a TV show with a similar theme: a spaceship is on its way to outerspace, but what the crew does not know is that they are actually inside a bunker on earth as part of an experiment.

Not a fake mission to Mars, but a Hollywood movie about a fake mission to Mars.