According to interviews, Sam Neill explained what made him decide to make the film was the scene in the screenplay in which the businessmen vampires buy morning coffee spiked with human blood.
The makers of the movie hosted a contest in Worth1000.com (famous photo manipulation-contest site) to come up with images of how the world would look if nearly everyone were a vampire.
In real life, Ethan Hawke had recently quit smoking cigarettes but his character, Dalton smokes several times throughout the film. Hawke therefore smoked soluble cigarettes during these scenes.
The News footage playing in Edward Dalton's car showing the vampire riots over blood deprivation was not filmed for the scene but was instead stock footage of actual riots being put down by actual law enforcement.