Hey dude, read the whole crazy story here
Probably the most amazing thing about that is how generally good the production is and how solid the performances. I gather Corman used two cameras for it, shooting both sides of a two shot at the same time - which, apparently, he rarely did to save money on film.
Here's a random tidbit: if people are isolated in an environment without any day/night cycles, so they just sleep when they get tired and do whatever whenever they wake up, people naturally adopt a 25 hour day. Though some people say it is shorter than this. Pretty interesting.