Due to memory constraints, the World Trade Center towers were not included in the New York skyline. In an eerie coincidence, the in-game story told of the Twin Towers being destroyed in a terrorist attack, exactly one year before the September 11, 2001 attacks.
Warren Spector did not much care for the opening music. While planning to tell the composer to do something different, he realized he could not get the melody out of his head, and so decided to leave the music as it was.
The entire game takes place at night; the only exception is the scene at the end of the Hong Kong missions where the helicopter picks you up, which is set during the day.
Thanks to its structure, which gives players the freedom to find different solutions to problems, it is possible to finish Deus Ex without drawing a weapon.
Many elements in the game are based on real conspiracy theories: the Illuminati, the Trilateral Commission, black helicopters, the Men in Black, Area 51/aliens, FEMA camps, government-engineered diseases/disasters and Majestic 12, among others.
The design of the robots was inspired by the ED-209 robot from the 1987 film RoboCop.
A large portion of the game's content makes references to Greek mythology or history.