An unused song can be found in the game's files that is a remix of the Results theme from the first Silent Hill.

Upon completing the game once on any difficulty, additional costumes for Heather become unlockable via cheat codes entered on a new menu accessible from the title screen. Exclusively for the PlayStation 2 version of the game, 14 codes were released as promotional tie-ins with 8 North American and 6 European video game media outlets, with each outlet's costume adorned with their respective logos. The participating companies and the codes to unlock their costumes include:

North America:
• Electronic Gaming Monthly, an American magazine, "EGMpretaporter"
• Game Informer, an American magazine, "gameinformer"
• GamePro, an American magazine, "ProTip"
• GMR, an American/Canadian magazine, "GMRownzjoo"
• Official U.S. PlayStation Magazine, an American magazine, "SH3_OPiuM"
• PlayStation Magazine, an American magazine, "badical"
• IGN.com, an American website, "IGN_pickleboy"
• GameSpy.com, an American provider of online multiplayer and matchmaking middleware, "iaml33t"

Europe:
• 13ème Rue, a French cable network, unlocked with the code "Suspense"
• Game Reactor, a Scandinavian magazine, "SH3_Wrestlarn"
• Play, a British magazine, "sLmLdGhSmKfBfH"
• G@me Network, an Italian cable network, "IwannabeaGJ"
• Official UK PlayStation 2 Magazine, a British magazine, "extra_thumbs"
• PlayStation 2 Revista Oficial - España, a Spanish magazine, "MATADOR"

During development the player could hear the sound of a crying baby Spoiler:on the third floor of the Hilltop Center., although it was removed in the final release.
The HD re-release includes a similar sound when Spoiler:Heather meets Claudia for the first time.

Heather Mason was named after Heather Morris, the person who provided the voice and motion capture for the character.

The sound that the Closer makes is that of a rhinoceros mixed with digital effects.

The map for the church was actually drawn by a child. The boy was the son of a friend of one of the game designers.

Shingo Yuri, the character designer, based Heather's appearance off of Sophie Marceau and Charlotte Gainsbourg. Douglas Cartland was based off of Father Vito Cornelius from The Fifth Element.

The character design for Claudia went through many changes, including one where her head was shaved and her body was covered in tattoos. Spoiler:It was deemed that this made her malevolence too obvious, and they simplified her design.

When you beat the game, you can enter a code to unlock a special costume for the New Game+. The code "PrincessHeart" has Heather wearing a superhero outfit. In the PS3 or Xbox360 version, there is an achievement/trophy for wearing the outfit called "Where's Luna?", which is a reference to Sailor Moon.

A cutscene can be unlocked if the memory card in use has a Silent Hill 2 save file. Heather contemplates reaching into a toilet, but can't bring herself to do it. She looks at the camera and asks, "Who would even think of doing something so disgusting?" This is a reference to a scene in Silent Hill 2, in which James Sunderland reaches into a toilet to retrieve a wallet.