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.
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.
In both this and his previous film The Return of Swamp Thing (1989), Louis Jourdan played a man obsessed with reversing the aging process to achieve immortality.