At one point, Zsolt Nagy's character accidentally hits one of the columns. This wasn't in the script, and the director decided to include it in the movie.
Gábor Herendi who plays one of the ambulance crew, is a famous director in Hungary.
First hungarian film on the Cannes Film Festival in the past 20 years.
Cameo: [Gábor Herendi] one of the paramedics examining the first jumper's remains on the metro railway.
Gábor Piroch, the famous Hungarian stuntman, left the Terminator 3: Rise of the Machines (2003) production for two days to help with this Hungarian production.
There are no clues who or what the evil Árnyék character is.
The stunt work at the end of the "railrun" between Bulcsú and Gonzó, when the underground almost hits Gonzó is real, and no special effects where used.
Some of the vocal effects at the end credits music, are done by the director.
The film includes an introduction by the director of the Budapest Metro (where the film was shot), who says that the film is a work of fiction and that employees of the Metro don't behave as shown.
Cameo: ['Péter Bergendy' (film director)] a bearded ticket inspector sitting at a table during the staff briefing scene.
On two occasions there is a robotic voice in the background saying (in English), "The next stop is: Concourse A... the color coded maps and signs in this vehicle match the station colors... please move to the center of the vehicle and away from the doors." The voice is that which was use until 1994 in the "people mover" underground trains at Atlanta's Hartsfield International Airport.