Due to memory limitations, the World Trade Center towers were excluded from the New York Skyline, eerily enough the in-game story explanation was the Twin Towers were destroyed in a terrorist attack, a full year before the September 11, 2001 terrorist attacks on the United States.
The entire game takes place at night - apart from when the helicopter picks you up at the end of the Hong Kong missions, which occurs in daylight.
Due to the game's emphasis on allowing players the ability to search for different solutions to problems, it is actually possible to complete Deus Ex without drawing a gun.
Warren Spector wasn't very fond of the opening music. He was planning to tell the composer to come up with something else, but discovered that he couldn't get the tune out of his head. This convinced him to leave it as was.