Continuity mistake: During the scene where Damaskinos is talking to his lawyer, there is a lot of the jello-like blood substance on his plate. However, when he gets up to go to the pool of blood, there's nothing on the plate.
Continuity mistake: When Blade is fighting the henchmen near the end, he lifts the last surviving one into the air and you can see Blade's hand through the henchman's throat and it is obviously a dummy. Then, when he falls backwards, his hand is not on his throat, it is on the henchman's shoulder.
Visible crew/equipment: When Blade is entering 'the house of pain' where all the vampires are dancing, a crew member is seen at the bottom right hand side of the screen behind a table, pushing a button which makes the door go up for Blade. (00:35:10)
Revealing mistake: When Blade slices Reinhardt in half, as the sunglasses fly off the two halves of his face you can briefly see that Reinhardt (or more precisely the CGI model of him) has no eyes. (01:37:23)
Answer: In Blade I we saw that with sunscreen and the avoidance of direct exposure Deacon Frost and his lackeys could go out by day. The reapers are probably two or three times more sensitive than normal vampires so the exposure was probably not long or direct enough to kill the regular vampires.