David S. Goyer explained in the DVD commentary that when Karen Jensen wakes up at Blade's hideout after her attack and rescue by Blade, the script had her discover a jar with a vampire baby in it. The baby would be alive and used by Blade and Whistler as a guinea pig for testing out weapons to fight vampires. The studio however found the concept to be disturbing and refused to allow it.
According to Wesley Snipes and Stephen Dorff on the commentary track, there was a slight clash between Snipes and Dorff while filming the hostage scene where Blade and Frost first meet in person. It was Dorff's first day, and while he was trying to establish Frost's motivation, approach, etc. Snipes became impatient and tried to counsel Dorff. Dorff became incredibly frustrated and said he felt overwhelmed since David Fincher and other notable filmmakers visited during filming and added further tension to the frantic on-set nature, forcing Snipes to assert his producer authority and make decisions. Snipes would tell Dorff that it was essential to trust in him, not only as the starring lead but also as producer. Snipes goes on in the commentary to say: "For a while...there wasn't that trust."
The scene where Karen and Deacon are talking about the cure for vampirism initially ran a bit longer and answered the question of how the vampires would feed if everybody was turned into a vampire. They would keep some humans alive in giant blood bags to harvest them. The bags can still be seen in a doorway during the scene, and later played an integral part of the plot in Blade: Trinity (2004).
When the bed opens up and reveals Vanessa (Sanaa Lathan), the sound effect used is lifted from Aliens (1986) (the scene where Ripley & Co. wake up on the Sulaco). Lathan would later appear in AVP: Alien vs. Predator (2004).
When Blade is first engaging Frost, he is seen charging up the ramp with his ninjato out and away from him. This is the correct way to run with any sharp instruments to prevent accidental death by impalement if said instruments are dropped while running.
In the film, Whistler can read the ancient Vampire Language. We see this when he translates the piece of paper taken by Blade from the archive room. However in the script, Whistler cannot understand the language and Blade goes to a Voodoo priestess to get a translation.
In the scene where the doctor first meets Whistler, Blade can be seen holding a map of New Orleans. This not only implies the city they are in, it is an homage to the comic books; many stories in the Blade series occur in New Orleans.
In the commentary, David S. Goyer says that Stephen Norrington called him to inform him that they needed to get together to collaborate on the film. Upon meeting Goyer, Norrington began taunting Goyer about how "tattoos aren't tough." Norrington then began flaunting his various piercings and deriding Goyer. Goyer concludes by stating "...that's Norrington, in a nutshell."
Michael Morbius was planned to be used as the main antagonist in a eventual sequel, but the idea was dropped out due to the fact the character's rights belong to Spider-man universe, and their movie license were property of Sony at the time. The vampire at the rooftop in the alternate ending of the movie is Morbius.
The film is not a remake of Mannaja (1977) aka "A Man Called Blade". The main antagonist in that film Blade (Played in that film by Maurizio Merli) is a bounty hunter, but Blade in this film is a vampire hunter. 1 thing that both characters have in common: they both seek to avenge a parent.
The trivia items below may give away important plot points.
The first cut of the film which was 140 minutes long had a disastrous test screening with audiences, and heavy edits and re-shoots were implemented which delayed the release date more than half a year. The most significant change was the addition of the final sword fight between Blade and Deacon Frost, which did not exist in the original version of the movie.
In the ending as it was originally planned, Frost turned into La Magra and became a large swirling mass of blood instead of keeping his form. This was scrapped because they couldn't get the special effects to look right. It can be seen as a special feature on the DVD.
Stephen Norrington: During the chase with officer Krieger, the vampire on the side of the road biting the girl's neck. In the alternate ending on the DVD, the blue figure in the black coat on the roof is Norrington again, as an unnamed vampire.
When Frost kills Krieger scene at the pool party ends, the camera focus in a vampire rubber bat toy. The bat toy is part of a Spider-man 1994's animated series line of action figures called "vampire Wars", which an action figure of Blade was includes. The vampire bat in the scene were a piece of an Spider-man transformed in vampire monster action figure.
In the narrative behind Blade being in Moscow in the final scene: Blade left the United States to find Whristler, when Blade learns that the vampires are keeping him alive and Blade was following the trail. See: Blade II (2002).