How do you contract people to work in films if the actors are all from different nations?

How does it work? Not only that I'm going through a number of countries to make the film so how does the contract laws work? What happens when everyone goes back to there home country ect?|||Contact the Screen Actors Guild. www.sag.org|||When a film company brings someone from another country to the US to film they are on a work visa. After the shoot they go home and collect checks. Each film company has provivions in place for foreign actors.