Mamuwalde tells Willis after he becomes a vampire that his reflection cannot be seen. However, Mamuwalde's reflection is seen when he leaves Justin's party, first when he passes a glass display case and again when he is walking down the street by store windows.
When Mamuwalde strikes Sheriff Dunlop, the stairs that he falls onto switch from carpeted to non-carpeted.
When Blacula hits the policeman and knocks him down the stairs, he lands at bottom of them. A few seconds later, he's nowhere to be seen.
Although Michael Conrad is credited as "Sheriff" Dunlop, several of the characters call him Lieutenant.
During the party scene, Mamuwalde's reflection can be seen in the patio doors.
Although the film is set in Louisiana, the policemen all wear LAPD-style uniforms.
Mamuwalde was imprisoned in a coffin by Dracula in 1780 and only released in the previous film (which took place in 1972), meaning that, between the two films, he has been active in the modern world for only about one week. Yet in this film, he plays Beethoven's Moonlight Sonata (composed in 1801) on the piano, a song he is unlikely to have heard, much less learned how to play.
Although the film is set in Louisiana, the street signs make clear that Mamuwalde is flying in bat form and/or walking around in the Westwood neighborhood in West Los Angeles.
Mamuwalde makes a serious tactical error by attempting to have his vampire curse lifted at Willis' house. If he had been successful, he would have become a mortal man trapped in a house full of vampires. He should have let Lisa take him to a place of her own choosing for the exorcism.