There's a file in Majora's Mask that contains an external bank of special map textures for places like the Mayor's office, or Termina field, even. I don't think it's its own file, however. No clue why, just somewhere else to store map textures. Flotonic was actually the one who found it. Apparently it's overlooked information, even though it's public.
At 0xC58BA0 in a decompressed (U) [!] Majora's Mask ROM is a table for external texture files. Look at the second byte of the header command beginning with 0x11 in a scene file. If it's greater than 00, multiply it by 8 and add it to 0xC58BA0. That offset will show you to the start and end offset (XXXXXXXX YYYYYYYY) of the external texture file that the map uses.
Look in the display lists for G_SETTIMG (0xFD) commands with pointers that don't use bank 02 or 03. They will point to within the external texture file.
This category currently contains no pages or media.