When Grost is forging a sword from the steel cross, the temperature is much too low to be forged based on the color of the steel which appears to be room temperature. He then sharpens the sword and then quenches it -- two steps which should be reversed.
Not sure exactly when the time period is, but there is what appears to be a concrete road in the cemetery. According to Google, concrete roads were first used in 1865.
At time 1:04:40, as the young girl puts the lamp down on the table, you can briefly see the electrical cord fall to the ground from under her arm, where it was hidden while she walked down the steps.
Although Isabella's surname is spelled Sorell (with one R and two Ls) in the end credits, her grave marker in the film lists her name as "Isabella Sorrel" (with two Rs and one L).
Grost suggests that the vampire may be using 'mesmerism' or 'hypnotism' to subdue its victims, but neither term was in use until the early 19th century.