Herzog once promised to eat his shoe if a certain young American film student went out and actually made the film he was always only talking about. The young student was Errol Morris, who met the challenge with his off-beat 1978 pet cemetery documentary Gates of Heaven (and went on to make The Thin Blue Line and Fast, Cheap and Out of Control ). Herzog makes good on his promise in this film.
Herzog has something of a track record with this type of bet. When making "Even Dwarves Started Small" he promised his actors that if they all survived the shoot he would jump into a cactus patch for their amusement. They did, so did he, and he claims to still have some spines in his body as a result.
Included as a bonus feature in the Criterion Collection's DVD release of Burden of Dreams (1982).