Mickeyjunk Mountain is the Wasteland version of the Matterhorn ride from Disneyland. It is the location where Oswald the Lucky Rabbit puts every piece of Mickey Mouse-related toy, game, or souvenir that comes into Wasteland. As the name suggests, it sounds like "Mickey's junk", as Oswald refers to it when you first meet him. High atop, on the uppermost peaks, there resides Oswald, stewing in a constant reminder of his "brother's" endless success. Also on the Mountain is the jug in which the Shadow Blot has been sealed. Oswald stays on the mountain to guard the jug and make sure the Shadow Blot doesn't escape.
The Mountain is divided in four sections: The Heaps, The Piles, Mt. Osmore Slopes, and Mt. Osmore Caverns. Each one of these has a key quest that will help Mickey reach the top of the mountain. In the Heaps, Mickey will have to Power the Crane by freeing Gremlin Kip or painting the three TVs hidden across the environment. In the Piles, the player has to climb the mountain and progress through a kind of factory where Beetleworx were produced. In the Slopes, Mickey has to take care of the Blotlings or power the gate to the Caverns area by painting two TVs in a maze-like place. Additionally, the player can find Gilda's climbing axe in a hut there. In the Caverns, Mickey only has to climb a long stairway and pass through three of Oswald's old cartoons to meet with him.
- Gremlin Kip lies far to the back of the first part of Mickeyjunk Mountain, over a precaucious platforming on a sea of thinner. Using a Clock Sketch helps due to the toys sinking once you get on the first one. After freeing him you won't have to do the main quest of TV sketch placement because he fixes the crane!
- Bunny Children aren't annoying if one or two are on you, even if they do slow you down. If they have enough to surround you though they will pick you up and toss you into the thinner. A swing attack and TV Sketch is all you need to get past them or push them to the thinner pool.
- There are some old NES and SNES Mickey Mouse cartridges on the mountain.
- Even though it's based on the Matterhorn, the bobsleds are not present at any part of the mountain although elements of it can be found in Oswald's Sanctuary.
- In Epic Mickey 2, it can briefly be seen in the intro from Yen Sid's land model.
- In Mickeyjunk Mountain, there is a red treasure chest on a cliff that has a thinner waterfall blocking it. When you find the TV by the Super NES games, there is a book that has an @ sign. If you thin it away, it shows three different sets of numbers: 512, 349, and 033. If you dial 349 it stops the waterfall briefly for you to get the chest which contains a silver pin. You will notice another phone when you're inside the Mickeyjunk Mountain. Dial 512, the crane will stop moving and form a path for you to cross a higher platform. You will find a golden pin there.
- Outside Oswald's sanctuary, you can find a hand holding an anvil. if you thin it, the anvil will set off a power panel setting of some platforms. Jump on the platforms to get to a thinner river. hop over the river, and paint in an anvil. doing so allows you to enter Gilda's hut where her climbing axe is located.
- You can use Gilda's axe to climb up to some statues, including one of Mickey wearing his wizard's robes and hat, holding a thinner bottle. However, doing so means failing her quest.
- You can thin out his statue, but it will drop the bottle. If you jump onto the the bottle, then the statue's hat, you can jump to a chest with a gold pin inside. This resembles what Mickey made in the beginning.
- To the left of the entrance of the sanctuary, there is a yellow poster with Mickey's face on. You can walk right through it, leading to a secret basketball court, with a gold pin and a blower which blows you through the hoop, and getting the humorous concept art "Epic Mickey", a doodle of Mickey defending himself from some kind of monster, probably a Spatter, by throwing something at it. It also has the words "By Chase" with the letters the wrong way round.
- There is a glitch in Oswald's sanctuary: Even if Gilda's axe is returned, you can still access the secret area beneath the Oswald picture on your second visit.
- In Oswald's sanctuary there are two large Mickey toys, if you jump on them they play different sound clips that were from the toys they were based on.
- Curiously, on Oswald's throne there is a T.V. showing Steamboat Willie.
- In early drafts, the yeti from the Matterhorn Mountain ride would actually be a robot piloted by Oswald to block entrance from Mickey. It was scrapped "due to reasons of scope".
- In Epic Mickey 2: The Power of Two, the player can no longer gain accesses to Mickeyjunk Mountain. Due to the earthquake caused by the Mad Doctor damaging the mountain, it seems too dangerous to go to Mickeyjunk Mountain.