The idea of the reapers having stingers coming out of the mouth were inspired by polish folktales where the vampires had a stinger or "finger" coming out of the mouth that they used to suck blood rather than use teeth like the Balkan genus that is the greatest influence on the modern vampire mythology.
Pop Icon Michael Jackson was originally going to have a cameo in the "House of Pain" sequence as a "Vampire Pimp" that Nyssa encounters as she searches the upstairs hall. Jackson had to drop out due to scheduling conflicts and the part was played by a Czech actor. The sequence was ultimately cut out entirely for pacing reasons.
When Damaskinos mentions the virus that causes vampirism, he says "parvovirus", though the closed captioning says "horrible virus" because of the obscurity of the term. Parvovirus IS a true virus type, and meets all the requirements for creating vampires in a fictional environment. The term was too obscure for most people to recognize, other than experts in virology.
Wesley Snipes was not always available for each day of filming for this movie, which came out in 2002. During 2002, Wesley starred in 3 other films aside from Blade 2. Instead of waiting for Wesley to become available, the crew shot another actor (who was not Wesley's stunt double) for scenes where it was not necessary to see Wesley's face. The first scene being where Blade, Scud. and Nyssa are riding in the helicopter to meet Damaskinos. The second was after Nyssa performed an autopsy on the dead reaper and confronts Blade in his quarters about his attitude toward the Bloodpack.
During the fight with Nomak in the church part of the House of Pain, the stained glass window is a replica of Dr. Strange's (another Marvel character who battles the occult) medallion, The Eye of Agamotto.
In the scene before while entering the vampire club with the Bloodpack, a large neon sign can be seen on top of a building that says, in large red letters, "Radoo". The history of Vlad the Impaler (whom the legend of Dracula is largely based upon) talks of his brother Radu. This name is also often associated with vampire movies as it is deeply ingrained in the Dracula story.
The look of Damaskinos is based off Nosferatu and the idea of his skin looking like old marble. The look for Nomak and the Reapers were based off numerous incarnations of drawings by Guillermo del Toro and concept artists, but primarily based off the mutants from Beneath the Planet of the Apes (1970).
David S. Goyer's original idea was to use Morbius as a primary villain, but Marvel decided they wanted to retain the rights to make an entirely separate franchise out of Morbius - i.e. a Morbius film, so the story was changed slightly and Jared Nomak was created to be used as the primary villain instead.
According to Wesley Snipes on the commentary with Goyer, there were four fight choreographers: Donnie Yen, who choreographed the "wire fu-esque" sequence with Blade and Nomak in the cathedral in their first fight; Jeff Ward; Clay Fontenot; and Snipes himself. Goyer remarked that there was a "wonderful rivalry" between Yen and Ward/Snipes/Fontenot.
The early scene in which Scud is watching The Powerpuff Girls (1998) was originally written with him watching an episode of Speed Racer (1967). However, the owners of the domestic rights wouldn't allow it.
In the DVD commentary, Guillermo del Toro said he paid homage to Dr. Manhattan from Watchmen and the book I am Legend. A reaper explodes similarly to the way Dr Manhattan explodes and the heroes were bombarded by reapers, much like the zombies bombardment in I am Legend.
When Blade returns to his headquarters early in the movie, Scud remarks "The Dark Knight Returns!" This is a reference to another comic book character that hunts by night, Batman, who was the subject of a classic comic book miniseries by that title.
Blade himself wears Oakley Four sunglasses, the ninja-style vampires who descend near the start of the film to offer Blade a truce are wearing heavily modified Oakley Overthetops, Reinhardt sunglasses are Oakley Square Wires and a further appearance can be seen fleetingly being worn by the fat, bearded vampire towards the end of the film, he is wearing Oakley Mars. All these appearance of Oakley sunglasses throughout of the film are apparently down to Wesley Snipes being big fan of the brand though his sunglasses in Blade (1998) were a pair of BlackFlyz.
When Rush takes Blade to the place where Wistler is held, he speaks "vampire language" through the door for the other one to open. He clearly says "Torrentetres" which is a reference to the Spanish film Torrente 3: El protector (2005) which was in production at the time, and which was directed by Santiago Segura (actor who portrays Rush).
Nyssa use's two Sa Vs. 61 Skorpion's. Reinhardt- two heavily customized Beretta 92fs with blade modifications,and a Remington 870 marine magnum "Stake gun". Asad-colt model 727 fitted with an M203 grenade launcher. Chupa-M16A2. Priest-Colt Double eagle. Verlaine- Heckler & Koch MPK5. Lighthammer- Heckler & Koch MK 23 Mod 0.
The clock seen on the back wall of Damaskinos' lair is a reproduction of the Orloj, or astronomical clock of the city of Prague. It's purpose is not only to tell the time but also to show the Earth's position relative to the sun, moon and the cosmos.
Reinhardt (Ron Perlman) exposes his gloved hand to a beam of sunlight and it burns his skin regardless of the protection of the glove. In the first Blade movie Deacon Frost (Steven Dorff) and crew go into the sunlight with leathers and make up with no ill effects from the sun.
Wesley Snipes: [Sun Tzu] Snipes' quoting of Sun Tzu - "Keep your friends close, and your enemies closer," follows references to the works of Sun Tzu in many other Snipes movies including Passenger 57 (1992), Rising Sun (1993) and The Art of War (2000).
The final scene, where Blade hides behind the Bunny Booth glass waiting for his victim (Rush), is incredibly similar to a scene in The Crow: City of Angels (1996) where the crow does the same. Both movies have many similarities in set-pieces and costume design, yet this scene is almost identical in both films. It's plausible to concede that after the critical and financial failure of this first Crow sequel, David S. Goyer could include this scene without scrutiny; having written both films as well.