This is what I love about a lot of Disney Parks, there are little things that general visitors won't have a clue about because they are too busy rushing around between rides without taking in a lot of the smaller details.
The Hidden Mickeys are a great example, many guests to notice the more obvious ones but even us Disney fans probably haven't found a lot of them yet. There's the little details like the names of Imagineers on Main Street, my particular favourite one is the "Contractor: Elias Disney 1901 (I think its 1901)" on the pavement of Main Street, it always brings a smile to my face.
Only the biggest Disney fans will know about Discovery Mountain and the reminants of the signs. I love the name Discovery Mountain but it just doesn't sound as exciting as Space Mountain.