Dick Maas was fired halfway through the production because of continuing arguments with producer Matthijs van Heijningen about casting and because Maas insisted that he do the music himself. However, Maas kept on working during that day and was rehired the day after, because Van Heijningen couldn't do it without him.
All the actors performed their own stunts, as there were no actual stunt men on this film. For instance, to keep the actors safe, the scene in which Gerard Thoolen's head gets stuck between the elevator doors was filmed backwards. A steel bar was placed below the elevator as a safeguard, but there were genuine concerns whether the bar could actually hold the elevator if it broke loose.
Dick Maas composed the entire score on two borrowed synthesizers: a Jupiter 8 and a Juno 60. Recording only took one day. According to Maas, producer Matthijs van Heijningen originally wanted to hire 'some other band' to score the film, but finally conceded when Maas proved to be more cost effective.
Apart from the elevator interior and a tiny piece of elevator shaft, the entire film was shot on location. Production designer Harry Ammerlaan managed to dress the same hallway in numerous different ways to resemble different floors in the building. They kept the floor wet constantly to keep it shiny and more ominous.
Dick Maas needed the help of an elevator manufacturer to make the film, and Schindler Liften BV liked the idea and gave their full cooperation.