diff --git a/graphics/door_anims/unknown.png b/graphics/door_anims/unused_battle_frontier.png
similarity index 100%
rename from graphics/door_anims/unknown.png
rename to graphics/door_anims/unused_battle_frontier.png
diff --git a/src/field_door.c b/src/field_door.c
index 70d10b7530..756d0dabf1 100644
--- a/src/field_door.c
+++ b/src/field_door.c
@@ -98,7 +98,7 @@ static const u8 sDoorAnimTiles_BattleTowerOld[] = INCBIN_U8("graphics/door_anims
 static const u16 sDoorNullPalette32[16] = {};
 static const u8 sDoorAnimTiles_BattleTowerElevator[] = INCBIN_U8("graphics/door_anims/battle_tower_elevator.4bpp");
 static const u16 sDoorNullPalette33[16] = {};
-static const u8 sDoorAnimTiles_34[] = INCBIN_U8("graphics/door_anims/unknown.4bpp");
+static const u8 sDoorAnimTiles_UnusedBattleFrontier[] = INCBIN_U8("graphics/door_anims/unused_battle_frontier.4bpp");
 static const u16 sDoorNullPalette34[16] = {};
 static const u8 sDoorAnimTiles_BattleDome[] = INCBIN_U8("graphics/door_anims/battle_dome.4bpp");
 static const u16 sDoorNullPalette35[16] = {};
@@ -202,7 +202,7 @@ static const u8 sDoorAnimPalettes_AbandonedShipRoom[] = {7, 7, 7, 7, 7, 7, 7, 7}
 static const u8 sDoorAnimPalettes_LilycoveDeptStoreElevator[] = {6, 6, 7, 7, 7, 7, 7, 7};
 static const u8 sDoorAnimPalettes_BattleTowerOld[] = {9, 9, 9, 9, 9, 9, 9, 9};
 static const u8 sDoorAnimPalettes_BattleTowerElevator[] = {7, 7, 7, 7, 7, 7, 7, 7};
-static const u8 sDoorAnimPalettes_34[] = {9, 9, 9, 9, 9, 9, 9, 9};
+static const u8 sDoorAnimPalettes_UnusedBattleFrontier[] = {9, 9, 9, 9, 9, 9, 9, 9};
 static const u8 sDoorAnimPalettes_BattleDome[] = {1, 1, 1, 1, 1, 1, 1, 1};
 static const u8 sDoorAnimPalettes_BattleFactory[] = {9, 9, 9, 9, 9, 9, 9, 9};
 static const u8 sDoorAnimPalettes_BattleTower[] = {0, 0, 0, 0, 0, 0, 0, 0};
@@ -256,7 +256,9 @@ static const struct DoorGraphics sDoorAnimGraphicsTable[] =
     {METATILE_Shop_Door_Elevator,                           DOOR_SOUND_SLIDING, 1, sDoorAnimTiles_LilycoveDeptStoreElevator, sDoorAnimPalettes_LilycoveDeptStoreElevator},
     {METATILE_Dewford_Door_BattleTower,                     DOOR_SOUND_SLIDING, 1, sDoorAnimTiles_BattleTowerOld, sDoorAnimPalettes_BattleTowerOld},
     {METATILE_BattleFrontier_Door_Elevator,                 DOOR_SOUND_SLIDING, 1, sDoorAnimTiles_BattleTowerElevator, sDoorAnimPalettes_BattleTowerElevator},
-    {0x3B0, /* TODO: Missing metatile ID */                 DOOR_SOUND_SLIDING, 1, sDoorAnimTiles_34, sDoorAnimPalettes_34},
+    // The metatile for this door doesn't seem to correspond to a door in any Emerald tileset. Given the surrounding door animations, it was likely cut from the Battle Frontier.
+    // From the palettes array we know it uses palette 9, and the door's shadow looks correct using either the Battle Tent or Battle Frontier Outside's 9th palette.
+    {0x3B0,                                                 DOOR_SOUND_SLIDING, 1, sDoorAnimTiles_UnusedBattleFrontier, sDoorAnimPalettes_UnusedBattleFrontier},
     {METATILE_BattleFrontierOutsideWest_Door_BattleDome,    DOOR_SOUND_SLIDING, 1, sDoorAnimTiles_BattleDome, sDoorAnimPalettes_BattleDome},
     {METATILE_BattleFrontierOutsideWest_Door_BattleFactory, DOOR_SOUND_SLIDING, 1, sDoorAnimTiles_BattleFactory, sDoorAnimPalettes_BattleFactory},
     {METATILE_BattleFrontierOutsideEast_Door_BattleTower,   DOOR_SOUND_SLIDING, 1, sDoorAnimTiles_BattleTower, sDoorAnimPalettes_BattleTower},
@@ -278,6 +280,9 @@ static const struct DoorGraphics sDoorAnimGraphicsTable[] =
     {},
 };
 
+// NOTE: The tiles of a door's animation must be copied to VRAM because they are not already part of any given tileset.
+//       This means that if there are any pre-existing tiles in this copied region that are visible when the door
+//       animation is played they will be overwritten.
 #define DOOR_TILE_START_SIZE1 (NUM_TILES_TOTAL - 8)
 #define DOOR_TILE_START_SIZE2 (NUM_TILES_TOTAL - 16)