

Since key items cannot be transferred with a Pokémon, they're unused and most have no effect in FireRed/ LeafGreen. A complete list can be seen on Bulbapedia here. Some of these seem to be early versions of other maps in FireRed and LeafGreen or just duplicates. Several other maps, some of which are corrupted leftovers from Ruby and Sapphire, also exist in the game's coding. The maps for Sevii Island 8 and 9 can be explored ingame by either changing address 02031DBC to 0x1DBD to 0x34 or 0x35 while going into any building or using the right code from the following table. They were probably cut early on in development.

8 and 9 still have intact maps with collision data, though they are obviously incomplete.

This implies that these were fully collisioned maps at some point, but they were "deleted" in the laziest way possible. Expanding the map size reveals one tile each of their original map intact, with collision data to boot 6 has a Surfable sea tile, and 7 has the impassible upper-left corner of a sea border rock.
POKEMON FIRE RED PLAYR DRIVER
The misspelling of the word "stereo" in the Driver Test from Ruby and Sapphire was fixed in the equivalent of FireRed and LeafGreen as well as of Emerald, being now correctly spelled in katakana (ステレオ) instead of hiragana (すてれお), and the entry itself was also moved to the bottom.
POKEMON FIRE RED PLAYR PATCH
To access it, patch 0x12f342 to 00 00 00 00 and 0x12f35c to 01 FF 09 08 in a Japanese FireRed v1.0 ROM to replace the New Game entry on the main menu with a call to Sound Check (this has the effect of running Sound Check after the title screen if there is no save file). At least Japanese FireRed v1.0 has the Sound Check like Ruby and Sapphire, except it was removed in localizations this time around.
