If you're just starting a production company do an S-Corp, but if you are making a film, and using other people's money then I would form an LLC or a Limited Partnership just for - and- only that film. Then your S-Corp can be the Registered Agent. When or if the suing begins you want as many layers between you and them as possible. The secret is C.Y.A. Just my 2 cents-and no I'm not an attorney so disregard everything I just said. I would recommend talking to an attorney it's worth a one hr consultation. Again a C.Y.A move. Unless you have an attorney in the family that will help you out. If you are in this (film) business to stay- find an entertainment attorney- YOU WILL need one sooner or later.
You can form an LLC yourself. The first time just buy one of those kits online then go to your states web site download the form fill it out-send in the fee, fill out a form for the Fed ID# and follow the instructions. Once you've paid the $50 for the kit and have done it the next time it only cost you the filing fee and your time.
Good luck