There is also Snoopy’s doghouse which was supposed to be a veritable palace as soon as you got past the humble exterior.
I just wondered how many types of things in movies, books, TV, etc. could the CS come up with that are (or are described to be) bigger and more spacious than their obviously humble exterior would allow.
I remember from playing D&D thirty(!) years ago that a portable hole was awfully convenient. Put the hole down on any surface, fill it with your stuff, then pick it up and be on your way.
There were quite a few places in Harry Potter that “didn’t fit”, mostly Wizardy places concealed in Muggle cities, though the most notable is probably 12 Grimmauld Place.
Transformers like Jetfire and Astrotrain. They would be about the same size as the others in robot mode, but when transformed into their jet forms, the others could ride inside of them.
The tree occupied by Clothahump (the turtle wizard, not the poster) in Alan Dean Foster’s Spellsinger novels is much larger inside than out, thanks to a hyperdimensional expansion spell. The wizard’s plastron is similarly enhanced, having drawers full of spell components and other things set into it.
But don’t put it inside any of your other extradimensional space devices, like your Bag of Holding, Heward’s Handy Haversack, or Belt of Many Pockets (the only extradimensional storage provider endorsed by Rob Liefeld).
I think 12 Grimmauld Place was just concealed, not hidden inside a warped space. The magic hiding it caused the minds of viewers to “stretch” their perceptions of buildings around it to cover its location. Sort of like the way we don’t perceive the blind spot caused by our optic nerves.