Matterhorn: About two-thirds of the way up the Matterhorn, there is a small attic-like space used as a staging and break area for climbers. Inside that cramped space is a basketball hoop, complete with backboard and net, which has been attached to a flight of wooden stairs.
There are several stories about how the cramped basketball court ended up inside the Matterhorn. The most popular speculates that the basketball court was installed to adhere to Orange County's strict zoning regulations for large structures. By turning the Matterhorn into a sports arena, regulations were met by qualifying it as a large sporting venue. However, neither the city of Anaheim or Orange County had any building codes or regulations that Disneyland would have been forced to meet or circumvent.
The boring truth is that the basketball hoop was placed there for mountain climbers and other Cast Members to pass time while waiting for scheduled climbing times or when bad weather prevented groups from scaling the Matterhorn.