No, Disney does not offer rain checks or any kind of compensation for a rainy day. This does not mean that your day will be ruined. There are still things to do at Disney when it does rain. Check out our article on 10 things you can do on a rainy day at Disney World.
Sometimes, the Disney waterparks may offer rain checks during heavy thunderstorms that close the park for most of the day. This is not guaranteed and is only in cases where the park may be closed most of the day.