No, the patent office does not do copyrights. Copyright is established when the piece of work is produced. It is not something that needs to be applied for. That said, without publishing something it's hard to prove that you wrote it first, which is what you'd have to show to make a copyright infringement claim. The process in Costa Rica might be different than in the U.S., but you should probably have some people you trust (preferably a lawyer) verify the piece of work, and then send a copy of it to yourself via registered mail using a sealed and tamper-proof envelope. Do not open it, ever. If you need to make a claim against someone, you'll have that for the courts to open. Copyright is the easiest of the intellectual property rights to obtain, but it can also be the messiest to prove in court. Your movie script idea is particularly hard because movie ideas tend to be vague and it's easy for different people to come up with similar ideas without ever crossing paths.