999: Nine Hours, Nine Persons, Nine Doors
999: Nine Hours, Nine Persons, Nine Doors
There are unused graphics in the game's memory that say "Seek a way out!". In the final game they were replaced with a movie featuring Junpei and the same text. It is unknown whether or not the sprites above were mere placeholders for the movie or if the sprites were scrapped in favor of the movie.
Contributed by MeleeWaluigi
In the steam engine room, examining a barrel under the staircase four times will have Santa make a reference to Donkey Kong.
Contributed by HelpTheWretched
The director of the game has stated that the events of the game take place in the year 2027.
Contributed by ORWELL6
According to an interview with 999's developer, the nine main characters are based on the Enneagram of Personalites. They are:

Ace is an Achiever (3)
Snake is an Investigator (5)
Santa is an Enthusiast (7)
Clover is a Loyalist (6)
June is a Peacemaker (9)
Junpei is a Challenger (8)
Seven is a Helper (2)
Lotus is an Individualist (4)
Ninth Man is a Reformer (1)
Contributed by BlogDog123
In the kitchen, when Lotus mocks Junpei for his lack of knowledge with appetizer plates and their usage, Junpei responds with "Well excuuuuuuse me, princess", a reference to the American animated series adaptation of "The Legend of Zelda".
Contributed by Naui