Since this is a Dogme-film, there cannot be any non-diegetic (artificial) sounds added, no post-production. The camera also needs to be hand-held. So when Christian falls to the floor in the reception and sees his sister, Christian himself had to hold the camera when falling. To achieve the "dizzy" sound, the original cameraman swung the microphone around in the air.
Thomas Vinterberg "confessed" to having covered a window during the shooting of one scene, which broke two Dogme rules: no bringing props onto the set, and no use of special lighting.
On March 28th, 1996 the Danish National Radio (DR) broadcast "Koplevs Krydsfelt" when an anonymous caller, "Allan", told his story about an unusual speech he held at his step-fathers 60th birthday. One of the many listeners to this strange story was director Thomas Vinterberg, who was inspired to make his first Dogme movie.
On 23 November 2002 Danish Radio found 'Allan' again. Allan met with director Thomas Vinterberg. During the interview it was revealed that Allan's entire story was pure fantasy. However, Allan had adopted the story from a true life experience of a Danish nurse. She held her speech on Christmas eve.
During the dinner with the speech, it was hard for the cameramen to fulfill the Dogme-rule about the cameras being handheld. The solution was to let some of the guests at the table hold the cameras themselves.