Both female leads suffer from social phobia. There are many scenes in Heart to Heart that are very similar to the scenes from Castaway on the Moon (the helmet and umbrella ones), the director probably got inspired by the movie.
Both are bittersweet comedies;
The characters are a bit over the top;
Both movies deal with problems of advanced societies;
They are funny and really enjoyable!
Just because both movies are about surviving on an isolated island. Although one is true story the other is more a comedy, Both have thought us some surviver skill.
Beautiful female leads on both movies were phobia or medical condition that prevent them from getting out of the house to live a normal life. The male leads were drawn into the curious world and fell in love.
Both movie has to do with stuck on an island, surviving and skill developed. Funny and hilarious. The different is that one is a group of people, the other one stuck on an island alone.
The female leads on both movies have inner issues. They struggle within, but the male lead came into their life. The male lead was struggle themselves as well