999: Nine Hours, Nine Persons, Nine Doors contains references to things that exist in real life. For example, Sheldrake is a real person. And it really is true that the Titanic had sister ships. This page has information about these things and more, with links to more information.
Seven says that maybe you're on the Gigantic, which was a sister ship of the Titanic. This ship really did exist, except it was known as Britannic. According to Wikipedia, this ship was originally named Gigantic, but was renamed after the sinking of the Titanic. However, the White Star Line always denied this.
As with the Gigantic, the Olympic also was really a real ship, and it really did serve in the war. However, it didn't hit a mine like it says in the game.
June mentions a book called Futility that has eerie similarities with the Titanic disaster in spite of having been written many years before it. Futility is a real book.
Kurt Vonnegut wrote about Ice-9 in his book Cat's Cradle. Although there really is a polymorph of ice known as Ice IX, it isn't solid at room temperature the way that Kurt Vonnegut's Ice-9 is in the story.
The stories of chemical compounds spontaneously changing all over the world has not really happened the way that it is described in the game. However, it is true that chemical compounds can spontaneously change if they are around other chemicals. This is known as disappearing polymorphs.
EDT: Ethylenediamine Tartrate
This is a real chemical compound, although it doesn't appear to have had any mysterious occurrences in real life like the one that Seven talks about in the game.
The person referred to in the game as Sheldrake really exists, and, in fact, was still alive as of the release of the game. Rupert Sheldrake is a real parapsychologist, and he really did come up with the concepts of morphic field, morphic resonance, and the morphogenetic field.
The BBC experiments really did occur. One was in 1983, and the other was in 1984 on the show Tomorrow's World. Another was later done on German TV in 1985. Read more about it at Morphogenetic Fields and Beyond.
Locke's Socks, Ship of Theseus
Things that DON'T exist in the real world
The following things were totally made up for the game and do not exist in the real world.
- All-Ice - While there are urban legends about a mummy that was aboard the Titanic and put a curse on it, they seem to be unfounded. The mummy in the urban legend was said to be that of the Priestess Amun-Ra. The name "All-Ice" was made up for the game.
- Dashiell Gordain - This is not a real person. He was just made up for the game.
- Funyarinpa - This isn't a real thing. It's just a word that Junpei made up. It doesn't really mean anything. Sorry, Funyarinpa.