Map 0xE7 from English Pokémon Red and Blue is a glitch map and a redirection glitch map when entered outside of the Nintendo GameCube's Game Boy Player that freezes the game without proper set up (see freeze glitch map). It has a map script of EAF1, which is Echo RAM for CAF1; and is within the 'sprite state' data.
Accessing it without a freeze
To access map 0xE7 without a freeze, perform the following steps (taken from Torchickens' forums post):
1) First get 202 Pokémon in the party (this is to place a C9 in memory at EC2B (CC2B) for map 0xE7's level-script pointer at EAF1). Without arbitrary code execution, this should be possible by activating Super Glitch while on the deposit option of a Pokémon Center's PC, depositing the Pokémon to get 255 Pokémon and then withdrawing a PC4SH to get 202 Pokémon (the ID of PC4SH).
2) Stand in the spot below, save and reset then put the party cursor to Pokémon 202 and close the menu.
3) Change D36E/D36F to 4112 and D35E to E7. You can do this with a TM31 x1 and X Attack x18 in the expanded items pack if you replace them with the Master Ball x199 (in item 33) and TM41 x79 (in item 41) respectively.
On a real Game Boy Advance SP and the Virtual Console version this map can act as a redirection glitch map; which sends the player to Pallet Town, forcing Oak's message not to step into the tall grass, having Oak loop around the screen and later forcing Red to spin into the grass west of Pallet Town, freezing the game.
The requirement of having 202 Pokémon may not be required on these platforms.
On a Game Boy Player (a GameCube peripheral) the redirection effect has not been observed, and performing the aforementioned steps will instead let the player explore the glitch map, which appears as a Glitch City with a glitch tileset with some tiles that may actively change while the menu is closed.
The map plays the Cinnabar Island music, despite being located in Rock Tunnel according to the Town Map.
Whether there is anything interesting in the map has not been documented and it is normally impossible to Fly away, however one can Fly away by changing the quantity of item 37 to 0 and then saving and resetting.
In order to avoid a freeze with a high chance of corrupting the save file and removing "continue" from the options box, one should always put the cursor on the 202nd Pokémon after entering the map before leaving the menu closed. There is fortunately a short time for the player to do this before the freeze occurs.
Unlike Map 0xFE (English Yellow), map 0xE7 in English Red/Blue is not known to corrupt meta-map scripts if entered without redirecting the player.