A Boy and his Dog (1975) starring a very young Don Johnson.

My interest was peaked in this film due to the upcoming Fallout 4.It came to my attention in a YT video I was watching about facts you didn't know about Fallout.

Here we have a post-apocalyptic scenario where a survivor (Johnson) has a companion,a telepathic dog and where the survivors live in cities underground.Sound familiar? It was quite bizarre in places but actually quite watchable.