Throughout the encounters with the "Lost Ones" and Dr. Alucard, it's made clear that vampires cast no image on reflective surfaces. However, when Vampire-Joker encounters Batman in the Blood Bank, Joker's menacing face casts a reflection in the containment beakers from behind a shelf in a POV shot.
It's not explained why Joker shows personality as a vampire, while the Lost Ones are all feral.
At the end, when the return of the 'Lost Ones' is being covered on the news, the police cars switch between shots from having 1 flashing light on the roof to 2.
When Batman and Dracula first meet and fight, dawn/daybreak is less than an hour away, and yet the low moon is full rather than a crescent.
It has been established that vampires cannot enter a home unless invited. Yet Dracula goes to Bruce Wayne's party (entering the house in mist form) without an invitation.
Security cameras should have been able to capture proof of the Lost One vampires attacking civilians, if not Dracula himself. They are often in public places that are monitored; playing possum until prey gets close.