The majority of the movie was filmed on the site of Montreal's Expo '67 World's Fair. This is the same location as the empty Man and His World Pavillion on St. Helen's Island. This island is connected to Montreal by Bridges and the subway. It was originally built for Expo '67 and remained standing there for several more years.
The pavilion was to be razed after filming was complete. Director Robert Altman had developed an affection for the silk-screened glass panels that he had used to heighten the lost-world sense of the movie's setting. He salvaged the 44 panels and for a time displayed them at his Lion's Gate studio. When he and his wife found an apartment in Manhattan in 1984, about a dozen of the panels - some as tall as 18 feet - became the dominant decorative feature. The history of the panels and the apartment, with photos, became an article in the March 1990 issue of "Architectural Digest", preserved online at www.sopot.org/altmanresidence.pdf.
The film's "Quintet" title refers to a board game which is a death game played by six participants involved in hide-and-seek antics in which the losers get killed by the winners, thus leaving five people (hence the word quintet which equals five).