While messing around with Intro Story Glitch, I found an
unused cutscene in DK's house (cutscene 1 in map 171/AB). The camera moves over to the corner to the left of the exit. Then it stays there for a few seconds and the screen suddenly fades out to send DK to the place with a Chunky pad in Crystal Caves.
I have found several things in DK64 that make no sense to me, but this trick (and a comment about the ice key on my video) had me thinking. The spot that the camera shows is where the
locker (or shower stall, I don't know what it is) with the Banjo-Kazooie poster used to be during the development.
It's pretty obvious that Rare was originally planning to have that locker/shower stall send the player to a secret place which held the ice key or the lock it was meant to open. The unused cutscene showing the spot where a beta object used to be and the warp to an ice-themed subarea are strong hints. Also, why would Rare bother implementing a cutscene warp to Crystal Caves from a place that isn't meant to have any connection to a level?
The small cave with the Chunky pad probably used to be separated from the rest of Crystal Caves. Warping there may have required a 101% completion of the game, or 100% if the ice key was to be obtained in Caves and ended up being replaced with the 201st Golden Banana.
Out of curiosity, I used a cutscene modifier to look for unused cutscenes in the ice key cave. Here's what I found:
Cutscene 15/F: camera slowly zooms in for 2-3 seconds
Cutscene 16/10: camera slowly zooms out for about 5 seconds
Cutscene 26/1A: camera slowly zooms in for 2-3 seconds, then stays still for about 12 seconds
Unfortunately, the cutscenes themselves don't activate anything, so it remains unknown what exactly was supposed to happen. The object(s) related to the ice key have been either completely removed from the map or placed somewhere out of bounds, so I don't know if you can interact with them using cheats.