From The Cutting Room Floor
Developer: Nintendo EAD
Luigi's Mansion is one of the first launch titles for the GameCube. After foolishly believing that he's won a mansion, from a contest he never entered, Luigi arrives to find that Mario has already been taken inside. Now it's up to Luigi to find and pull Mario out of this mess, while the ghosts who own the mansion try to scare him. Unfortunately, his only line of defense is a vacuum cleaner...
Basically, Mario is Missing! done right.
In the disc's "Iwamoto" folder (named after Daiki Iwamoto, one of the programmers), there are four unused maps in the directory. These maps can easily be loaded using Action Replay codes.
Test Map (Map0)
Can be accessed by Action Replay code VW2Q-7RAM-0QWEN Z5GB-DQ0V-FFE37. From the looks of it, the first room is heavily based upon an early version of the Foyer. There is a room to the left of Luigi, containing one of the Floating Whirlindas. Scanning his heart will freeze the game, however, and you can't capture him, as he doesn't appear at all.
In the main room is the ending painting of Mario (which does nothing when you get close to it), Shivers the Butler (if you haven't already captured him on the save file you're using), Toad (who does nothing), and King Boo without his crown. The fire in front of Luigi can be put out with water element shots (use an element modifier code since there's no water elements around), as it's the same fire used to block the exit from the Kitchen. The room looks like a cheap replica of the first room in the main game.
A room to the right contains another King Boo. However, walking in front of him will immediately crash the game, which can only be fixed by doing a hard reset. Inside the room to the front of Luigi are a bunch of tables. Luigi can walk through most of them, showing that the collision maps were not finished.
Leftover Early Gallery (Map5)
Accessible by Action Replay code AVBN-5Y5T-JFACD UE63-D6EX-YPA7J, this map has no light at all. One of the main differences clearly evident with this map is the Unicorn Statues, which look almost exactly the same as the ones where you fight Boolossus. However, their horns are smaller than those of the statues in the final. Also, the room where King Boo's picture hangs is much more dull and bland, compared to the final. Unlike the regular Gallery, this one is actually shorter than the final version's Gallery.
When using an Action Replay code which replaces the original gallery with this one, there were a few missing ghosts. They are the Clockwork Soldiers, Biff Atlas, Slim Bankshot, Sir Weston, Bogmire, Uncle Grimmly, Vincent Van Gore and Boolossus.
Leftover Early Gallery #2 (Map7)
This map can be accessed by Action Replay code K9WM-N4B1-B973A EHVN-PJW2-JG6RY EP6Q-M8T6-KYG96 2MXP-MFK6-NNQXB 086K-B3N9-CUZZD Q91V-15K5-JQ1ND. This looks relatively similar to the other early gallery, except for one major difference: it is much longer. This could have meant that at one time they may have had more portrait ghosts planned, which would have made the game longer. The doors, however, seem to be in the same position as the previous map, despite this map having its own file for objects.
Using another replacement code to replace the original with this gallery, all ghosts are present.
Even Earlier Gallery (Map8)
This map can be accessed by Action Replay code 9E9Q-3356-9PDKQ EHVN-PJW2-JG6RY 6H2X-YMGT-AZ97D 2MXP-MFK6-NNQXB NG04-GRD6-F2QNE Q91V-15K5-JQ1ND.
This is perhaps the earliest version of the Gallery leftover on the disc, even earlier-looking than the other early galleries accessible via Action Replay, or "Map7". The textures are massively different. This gallery is a slight bit longer than Map7's gallery, and no statues are present in the room, unlike the Boolossus unicorn statues that are in the two previous leftover gallery maps.
Surprisingly, E. Gadd appears in this map, but you can't talk to him, as he does nothing. What is very strange is that E. Gadd does not appear when using the Action Replay code. The doors are in the same position as the last two maps and the King Boo room is the same as Map7 and Map5. Because of the lanterns and the texture of the wall, this map might originally have been intended to have more of a crude and 'underground' look, rather than bright and flashy. Some of the textures, such as the brown wall, can be found in the training room. That could mean the training room was made around the same time as this version of the gallery and never changed. The model of the holes with dirt inside them, not shown in the photo, is also found in the training room.
Using another replacement code to replace the original with this gallery, the ghosts Vincent Van Gore and Boolossus are not present.
A simple debug mode is present in the game, accessible by using the code UH8N-EMX9-5BXTY GYXM-ZBFW-F4RDC (PAL) or 4W86-70XA-WTN2Y-MWC5-2BBB-FXB7E (NTSC / US.)
The debug mode brings up an info display in the top-left corner of the screen. The first line is a counter of how many milligrams of dust are in the Poltergust 3000 (lowered by exhausting dust). The second line is labeled as "Aura" or "Spiritual Energy" and displays the number of ghosts captured, including both portrait ghosts and normal enemy ghosts. The third line is labeled "Water", and the fourth line is labeled "Heart". While the debug mode is active, you can also see objects' Game Boy Horror scanning boxes.
Discover what the last counter means. Apparently there are ways to make it go up.
Early Mansion Image
An earlier design for the mansion can be seen in the background image used on the title screen. In the cutscene played at the beginning of the game, chimneys can be seen on top of the mansion; they are not present here. This implies that the title screen was created before the mansion's design was finalized.
E3 Game Boy Horror Clock
Found in the newtime and 2dsub directories under the folder Kawano (named for Masahiro Kawano, another programmer), inside the files game.szp and game_usa.szp are the image files for the Game Boy Horror timer that was cut out of the game. These numbers were also used for the similarly cut heat meter. When the timer runs out, it merely resets. This could have been created for the demo specifically, working as a time limit.
GBH Clock Radar
The border was at one time animated, as it used to be a radar that could track the direction of nearby ghosts. The image files for this can be found in the newtime folder, as well.
The clock radar can be viewed with the following Action Replay code:
Early Ghost Designs
Leftover in the Obake01 (Gold Ghost) and Obake02 (Purple Puncher Ghost) SZP files are two strange ghost design images; these are different from both the Final Gold Ghost, and the early Pink Ghost that once took its place. Either these could have been early designs for both ghosts, or these were new ghosts not seen in the final or the E3 version. It is more likely these were new ghosts, which weren't seen in E3, since their colors are brighter than any of the E3 ghosts used. For one reason or another, their images ended up into folders "Obake01" and "Obake02". These two ghosts are the only ones who have these leftover images.
Leftover in another folder of "game.szp" and "game_usa.szp" are some unused dialog icons. None of the above characters have lines in the game except for Mario, but at one point they could have. Mario's icon was possibly planned to be used when he says "Get me outta' hereee!" at the bottom of the well.
Found in "game_usa.szp" is an icon of Daisy, who doesn't appear at all in the game. This is a cropped portion of the official art of Daisy from Mario Tennis on the N64, as it was one of the most recent images of her at the time. The file was found in game_usa.szp in folder kt_static, called Test.bti. The icon was probably a test for the posters you vacuum off the wall, as it is grouped with the graphics files for the posters.
Found in the "Effect" folder on the game's root, not in an archive, is this... door. It bears no resemblance to the doors used in the game, which are actually in a model format that predates BMD (a format simply called ".mdl"). The texture on the knob is of Luigi's hand, and was most likely meant to be a reflection. The door has one animation - being opened.
Two other files, called door.mdl and door.key, are also present. Since there is no viewer for these file formats, it is currently impossible to tell if they are duplicates of the .bmd and .bck.
Find some way to view .mdl files.
These renders of Luigi can be found in the files for the ending.
This was most likely to be used for getting the lowest possible rank. There may be some connection to the "bad ending" from the E3 demo.
This was probably meant to be used when getting a good ending.
This was obviously meant to be shown for the best ending.
"And... a present from the doctor!"
This texture of a GameCube is loaded with the scenes for the boss ghosts, such as Chauncey and Bogmire. It is likely a placeholder graphic for the trippy background, as it only gets used for a moment. Interestingly, the disc cover on the GameCube has a see-through portion, which was the original design of the console as seen in the Super Mario 128 demo.
E. Gadd's Lab oddities
Using an Action Replay code, it is possible to control Luigi in the main room of E. Gadd's Lab. This makes it possible to see some oddities:
- Back in the lab, there are two doors. One can barely be seen in Gadd's normal cutscenes, while one of them is never seen. It reads "Training". Guess where it goes?
- Behind E. Gadd is a ladder. It might look like a decoration, but it's actually climbable. However, it leads nowhere.
- E. Gadd's Lab has a minimap, normally visible from the Gameboy Horror in the same manner as the one for the mansion. The only two places you can view it from are the Training Room and the Gallery, since in any other places you don't have control of Luigi.
This suggests that instead of just being a cutscene area, E. Gadd's lab was originally going to be explorable.
Lighting up the attic hallway
By playing around with some Action Replay codes, it's possible to turn on the lights in the Mansion's attic. In the final game, hallway sections only become lit after a boss of the area has been defeated - which, in this case, is the game's final boss. As such, the light there never goes on.
The codes that were used: All Doors Unlocked (Including spike doors), Always able to move, Luigi already has equipment, Ceiling Walk ON/OFF B+ D-pad up/down, Moon Jump (B), and Element Modifier.
Get screenshots, video, etc. There are some others from Japan to US. 
For whatever reason, the Nintendo logo is blue in the Japanese version.
The game is called Luigi Mansion in Japan. To accommodate the removal of katakana text, the words were spaced closer together in localization.
The PAL version of Luigi's Mansion has an entirely different Hidden Mansion mode. Everything is mirrored left to right, it's much, much darker, some ghosts that appear later in the game will now appear earlier in the game, and enemies have generally been made harder (and in the case of one boss battle, entirely different). Nintendo sure loves the Euros.
Woah!Luigi has a completely different sound for taking damage in the Japanese version, which is reminiscent of his grunt from the E3 demo. It's still present in the American and European soundbanks.
Other PAL differences include: Boos have different HP (and 45 Boos are required to reach the final room), there are fewer health pickups, the normal mansion's darkness was brightened (though the Hidden Mansion's darkness is more or less the usual NTSC darkness), and it is impossible to get an A Rank on the first playthrough since money distribution has changed. The Japanese version has a lot of minor audio differences compared to the other versions (see TMK). On a blue moon, the music doesn't even load, resulting in a haunting silence. Finally, the main menu does not include the "View a Pikmin™ Movie" option.