In 2020, an unused level was discovered in the PC version of the game called Ruins of Joy Town that was meant to be played after The Goblin Fort level, but before Joy Castle. The unused level appears to be mostly completed, but lacks background music.
Due to the Instruction manual mentioning a "young Tim", and the DS version having a Tim Drake character, the primary Robin in this game is most likely Tim Drake.

In the Game Gear version, during the fifth stage where Gunstar Yellow gets kidnapped, a billboard can be found advertising "Super C Spirits", appearing to be a reference to Super C.
The Sega Saturn version of the game contains hidden files that can only be accessed when loading the game disc on a PC. 15 pieces of character artwork and a text document containing messages from 13 of the Saturn version's developers including graphic artists, members of the sound team, and programmers can be found. The messages contain insights about their duties, goals and struggles in porting the game from the PlayStation to the inferior Saturn, with several members of the staff having just entered the video game industry and joined Konami prior to work starting on the port, and collectively having mixed to positive feelings about the final result, with most being happy with their work, while others feeling they had failed to live up to the PlayStation version. Regardless, much of the staff thanked players for playing the game and encouraged them to mail feedback to them at Konami.
Two notable details from these messages include:
•A story/rant shared by programmer Hideto Imai in the last and longest message about his experience in violating Japan's Motor Vehicle Storage Act by parking his car curbside while staying at his in-laws during development.
•A scrapped character idea shared by graphic designer Yoshinori Suzuki:
Two notable details from these messages include:
•A story/rant shared by programmer Hideto Imai in the last and longest message about his experience in violating Japan's Motor Vehicle Storage Act by parking his car curbside while staying at his in-laws during development.
•A scrapped character idea shared by graphic designer Yoshinori Suzuki:
"There's actually another version of Maria with a full set of graphics different from the one the player meets in the actual game. It ended up going unused. It might've been neat if she had been used, though. Because she was a dark version of Maria, the opposite to the light version of Maria, her attacks and such would have been entirely different. Go ahead and imagine for yourselves what she might have been like. (Perhaps, if she'd appeared in the game, she'd have been called Black Maria?)"
The PC port of the game featured a glitch that prevents the player from playing the game by crashing to the desktop. It was patched on November 25, 2021.
The Xbox 360 port of the game is the only version that natively supports 60 FPS. The framerate on actual Xbox 360 hardware is capped to 30 but can drop down to 9 FPS, because of the render distance and additional lighting. When emulated, the game maintains a steady 30/60 FPS depending on what's going on. Cutscenes, subtitles and loading screens move too quickly, and there is major slowdown when the game is running in 60 FPS. This is noticeable in the sixth level Ringling Village and the final level Showdown With Omegaton.
The game was released to the Wii as “Pajama Sam: Don’t Fear the Dark.”

Super Mario Advance, the Game Boy Advance version of Super Mario Bros. 2, was a launch title for the system and opens with a short cutscene featuring the playable characters walking and pulling up the game's logo from the ground. The cutscene features them walking in a small lit square, with the rest of the screen being dimmed until the characters are in place to start pulling up the logo, when the borders slowly brighten. The resolution of the bright square is 160x144 pixels, the screen resolution of the original Game Boy and Game Boy Color, with the fade-in meant to demonstrate the increased resolution of the Game Boy Advance.
In the European release of the NES version, pressing Right on the logo screen for the game's publisher Storm will trigger a secret set of credits menus. This screen can also be accessed during any cutscene by pressing Right after the message at the current cutscene is displayed and the program is paused before the next cutscene screen and waiting for the input to skip it. This occurs because the input waiting routine is the same for the logo and for the cutscene waiting screens. The Japanese version of the game has no starting logo and the cutscene input logic is changed, but the credits are still in the game and can be accessed through hacking.
Exclusive to the GameCube re-release is a set of unlockable bonus content colloquially referred to by fans as "The Three Secrets". The requirements for earning this content is as follows:
•All discoveries need to be found and reported
•The number of opened Treasure Chests must be at 90% or above
•All Crew Members must be acquired
•All Moonfish need to be captured and given to Maria's bird Piccolo
•All Wanted Battle bounties must be found, beaten, and reported
•Beat all four optional battles with Piastol and finish her story
•Defeat over 2500 enemies
•Defeat all four Sky beasts
•Win 12 non-story Ship Battles
Upon meeting this criteria, The Three Secrets can then be acquired:
1. The Mystery Merchant will now sell the Sky Fang sword to Vyse.
2. A secret discovery can be found on a peak of a rocky overpass in High Sky just outside of Sailor's Island. This discovery is a Golden Hamachou, and does not appear in the Journal after it is found.
3. At Crescent Isle, a hidden boss Spoiler:Vigoro, who in the GameCube version became an Air Pirate following his third encounter with the main characters can be fought.
•All discoveries need to be found and reported
•The number of opened Treasure Chests must be at 90% or above
•All Crew Members must be acquired
•All Moonfish need to be captured and given to Maria's bird Piccolo
•All Wanted Battle bounties must be found, beaten, and reported
•Beat all four optional battles with Piastol and finish her story
•Defeat over 2500 enemies
•Defeat all four Sky beasts
•Win 12 non-story Ship Battles
Upon meeting this criteria, The Three Secrets can then be acquired:
1. The Mystery Merchant will now sell the Sky Fang sword to Vyse.
2. A secret discovery can be found on a peak of a rocky overpass in High Sky just outside of Sailor's Island. This discovery is a Golden Hamachou, and does not appear in the Journal after it is found.
3. At Crescent Isle, a hidden boss Spoiler:Vigoro, who in the GameCube version became an Air Pirate following his third encounter with the main characters can be fought.
There is a hidden feature that allows Pit to haggle with Shopkeepers to lower the prices of items.
In the NES release, this is done by simultaneously pressing A and B on a second controller. In the Famicom release, haggling is instead done using a second controller with a microphone on it, by holding A on the second controller and speaking into the microphone to haggle. In the 3D Classics port for the 3DS, haggling can be done by simultaneously pressing the A button and either Start or Select.
The main catch to haggling is that the prices will only be successfully lowered if Pit's health is one point higher than the first number of the stage he is currently haggling on (i.e. Pit's health must be at 2 arrows when haggling in World 1 to successfully haggle). Otherwise, the Shopkeeper will raise the prices instead.
However if you fail to haggle, the prices will not change until the Shopkeeper's text finishes scrolling, creating a small window of time to buy something at its original price just before they increase.
In the NES release, this is done by simultaneously pressing A and B on a second controller. In the Famicom release, haggling is instead done using a second controller with a microphone on it, by holding A on the second controller and speaking into the microphone to haggle. In the 3D Classics port for the 3DS, haggling can be done by simultaneously pressing the A button and either Start or Select.
The main catch to haggling is that the prices will only be successfully lowered if Pit's health is one point higher than the first number of the stage he is currently haggling on (i.e. Pit's health must be at 2 arrows when haggling in World 1 to successfully haggle). Otherwise, the Shopkeeper will raise the prices instead.
However if you fail to haggle, the prices will not change until the Shopkeeper's text finishes scrolling, creating a small window of time to buy something at its original price just before they increase.
The SNES, Game Gear, and Game Boy versions of the game omit Colonel, Diesel, Leotsu, Nezu, and Auroch from the roster unlike in the Sega Genesis and Amiga versions, where in those versions have the character roster complete.
Both the Game Gear and Game Boy versions lack the Tournament Mode and digitized voice samples found in the console versions of the game.
Both the Game Gear and Game Boy versions lack the Tournament Mode and digitized voice samples found in the console versions of the game.

In 2021, a secret display mode for the PlayStation 2 version of the game was discovered that involves first setting the standard video output to 480p (through the "Progressive Scan Mode" option), and then starting a new game with the profile name "PSONE". Doing this will cause the game to lower the standard output from 480p to 240p and disable texture filtering, making it more closely resemble a PlayStation game. For unknown reasons, this mode is referred to as "Christian Slater mode" in the source code.
The game manual featured throughout every version's cutscenes (except the DS version) is the cover from the Xbox 360 version. The DS version, however, is actually from the in-game cutscenes used from every other version. Interestingly, the DS version’s cutscenes resemble the in-game ones from the other versions.
In the Canalave Library there is a Book that was not in the original games for the DS, called the "The Sea's Legend", that the game describes as being "recently discovered" and that states the mysterious following text:
Spoiler:"Once upon a time in the East Sea, there was a Pokémon known as the prince. A brave human asked Pokémon living in the sea to let them see the prince. Mantyke, Buizel, and a Quilfish with huge spikes acknowledged the human's bravery and joined them. Together, they set off in a boat over the sunset-streaked sea, sailing through the ocean gate stretched over the waves. News of this reached the ears of the prince, who went to meet the brave little party at the Seaside Hollow."
It's possible that this text was put into Brilliant Diamond and Shining Pearl Spoiler:to tease the upcoming game Pokemon Legends: Arceus via giving the player a hint of a storyline or event that may happen in the latter game's plot. Furthering the suspicious nature of the text, Game Freak, when sending out review copies of the games, forbid any reviewer from talking about any of the text in the library.
Spoiler:"Once upon a time in the East Sea, there was a Pokémon known as the prince. A brave human asked Pokémon living in the sea to let them see the prince. Mantyke, Buizel, and a Quilfish with huge spikes acknowledged the human's bravery and joined them. Together, they set off in a boat over the sunset-streaked sea, sailing through the ocean gate stretched over the waves. News of this reached the ears of the prince, who went to meet the brave little party at the Seaside Hollow."
It's possible that this text was put into Brilliant Diamond and Shining Pearl Spoiler:to tease the upcoming game Pokemon Legends: Arceus via giving the player a hint of a storyline or event that may happen in the latter game's plot. Furthering the suspicious nature of the text, Game Freak, when sending out review copies of the games, forbid any reviewer from talking about any of the text in the library.
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