Although many viewers take it for granted that the comet of the title is Halley's Comet, this is not specifically stated in the film. In fact, the comet of the title was the Great Comet of 1811 (formally designated C/1811 F1 by astronomers). Halley's Comet, which appears only every 75 to 76 years, appeared in 1758 and 1835; it did not appear in 1811.
Oscar winning composer John Barry wrote a score for the film, but it was rejected and a new one written by Hummie Mann was subsequently commissioned.
The original title for this movie was "A Very Good Year". Trailers were shown with that title, but it was changed prior to the movie's actual release.