I didn't have Mountain King for my 2600 so I looked it up. What a neat glitch. Platformer glitches are fun, I really enjoyed breaking the early Sonic games for things like the Hyper Sonic glitch, or some of the map glitches.

I think this is one thing about Super Mario Bros. 3 that felt so magical to me. With the addition of the hidden whistles and intentional "glitches" like crouching for an extended time on a white platform, running behind map elements, etc. you felt like some kind of plane walker just bending time and space to your will. Fantastic implementation of a level skip mechanism for veteran players. It gave an already incredibly expansive game quite a lot of extra replay value, just like Minus World.