The trivia items below may give away important plot points.
Prior to the movie's premiere at the Cannes Film Festival, director Michael Haneke predicted that two scenes would elicit the strongest reactions: the death of the fish, and the money being flushed down the toilet. The movie's producer agreed about the fish, but didn't believe people would care about the money. Haneke turned out to be right; during the money flushing scene, he witnessed several people leaving the cinema in shock.
Originally Michael Haneke wrote a narration that started with the suicide and was punctuated with flashbacks from the family's activities, but after 6 weeks writing he refused this idea because the flashbacks worked as explanations for the suicide and Haneke didn't want the movie to explain.
The last lines are translated to: "The S. [Schober] family was found on January 17, 1989. Subsequent to a request from the wife's worried brother, the door of the apartment was knocked down. On February 20, the family was buried. In spite of the letter left for the parents, they refused to believe it was a suicide and filed a murder complaint against Parties Unknown. The police investigation following up on this suspicion was without results. The matter was filed as an unsolved case."