The scene where Quinn (Donal Logue) attacks Karen in the hospital corridor features lots of screaming, but they knew something was wrong when Logue started yelling too. During the tussle, he fell face first onto the hard floor and completely dislodged his jaw. He had broken it in an accident years prior, and opening his mouth too wide and too fast can unhinge it. They were filming in an abandoned hospital but had to rush to a real one, "but I've got this guy who's dressed as a third-degree burn victim, essentially naked, running in with his jaw hanging down." The room cleared out pretty fast.
When David S. Goyer first pitched the idea of doing a Blade movie, the executives of New Line felt there were only three actors who could possibly do the role: Wesley Snipes, Denzel Washington and Laurence Fishburne, but in Goyer's mind, Snipes was always the perfect choice for the character of Blade.
A deleted conversation from the script explained how Blade's sword originally belonged to Whistler (Kris Kristofferson) who himself was part of a long line of vampire hunters.
Quinn originally had a much smaller role, but Donal Logue was so funny onset that his character was expanded and he was allowed to ad-lib a good portion of his dialogue.
David S. Goyer explained in the DVD commentary that the scene where Karen touches Blade's sword was originally longer as she went on to discover a weird, hybrid infant of some kind floating in a tank. It came with a jump scare, and Goyer says "I think it would have scared the living shit out of the audience, but New Line felt it was just too horrible."
Jeff Imada: (at around 52 mins) Martial artist/stuntman has a cameo at the vampire archives where he and several other familiars incapacitate Blade.
Stephen Norrington: (at around 40 mins) 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.