During their fist meeting with Van Helsing, he offers the men a cigarette from a cigarette box. He closes the lid and sets the box down on a table. In the next shot, the lid is open.
It is not possible to melt silver over a small propane camping gas stove as shown since it has a melting point of about 962 °C. The apparatus loses heat too quickly to achieve such temperatures. Molten metal at such temperatures glows with a white-reddish hue as a function of the temperature instead of remaining silver-colored as shown.
It is also not possible to use a lead bullet mold as shown because silver is much harder and more resilient than lead and thus cannot be trimmed off with the mold's trimming cutter as shown.
At the end, when Dracula disintegrates, a skeleton is shown that is completely just bones, nothing else. A moment later, a shot is seen where the skeleton now contains some skin and rotten flesh before completely disappearing.
Although a gunshot to the head is not always fatal, Professor Van Helsing appears to take one without any adverse effects and doesn't even seem to have spent any time at all in a hospital. He only wears a small bandage over the wound.
When Jessica is attacked by the female vampires in the basement of the sinister cult house, the brunette vampire menacing her from the rear is missing an important bit of anatomy- vampire fangs.