I knew youd say that. So I prepared this: A> sun copy_paste.exe
If you are reading this, you made the obvious assumption about the doors verses the barrel. Howeverm if you are reading this, you are about to be theoretically disproven. Not factually, actually, just in theory.
Sure the barrel in MMM you could walk around in, but in the left door, you can walk for a short distance to a sudden fall-death. Do you know how doors work in video games? The ones which do the jiggy-wipe actually have the exact same thing behind them or close to. When you run through them it shows banjo/mario/zelda whatever game you are playing running a short distance and then WARPING to the room stored in a different location. Thats how the inside/oustide rule is broken so easy. The big area isnt INSIDE the small area, its in a totally different location.
This is best demonstrated in Zelda
OT, when you jump off the drawbridge and into hyrule castle town, you will run longer than the solid floor before the warp is. Resulting in you falling down completely.
Now think about this, imagine doors in Banjo worked in the same way. Short stretch of ground- warp to secret room of some description, maybe secret level/sub level, maybe if it is removed it will crash or you will end up somewhere random like inside the giant beehive.
BUT it would only work if the activator for the warp is activated. The parachute wont open until you pull the cord.
Tower room A, SNS, WHATEVER. It all has the possibility of existing, and that door leading to it, but not directly BEHIND it.
Please excuse the multiplers erurs and my lck of hax1nk noelige.