The Disney Parks Blog detailed the queue of the Seven Dwarfs Mine Train. Per the blog:
First up inside the interactive queue is a jewel sorting station. As the jewels flow by in a 15-foot wooden sluice, guests will be able to drag them into different trays, matching them by color and shape (the gems come in four different sizes and six colors). Something to look for here is that a melody from the film “Snow White and the Seven Dwarfs” can be created when guests move from spigot to spigot. There are 12 spigots, inspired by the Dwarfs’ woodland friends, that each correspond to the notes of a musical scale.
Later on in the queue, guests will pass the Vault room. According to our friends at Imagineering, this is a nod to a scene in the film “Snow White and the Seven Dwarfs” in which [Dopey] hangs a key just outside the mine’s Vault room door.