The plane shown taking off in the opening credits is not the same type of plane shown flying in the air, and the plane shown landing is yet a third type. This could be a goof, but in the 1980s it likely would have been a connecting flight.
The phone in the castle is attached to the table, it's not connected.
When Radu is battling Frankenstein in the barn you can clearly see a remotely operated camera on a hinge moving in the upper left corner in the background.
All of the signs in Transylvania are written in English, and not Romanian.
About 36 min in, Gil calls Jack into his bedroom, and they check the window. As Jack returns to the door, saying "It's jet-lag; go back to sleep. The facts, Gil, the facts," the boom mic shadow is easily visible in the upper right corner (twice).
At the end of the movie it's explained that the Wolfman is really Lawrence Malbot, the son of the gypsy woman. The credits show the Lawrence Malbot as played by Rudy DeLuca, which is wrong. Deluca played the husband of the gypsy woman and the character Malbot is played by Donald Gibb. Lawrence Malbot is the Wolfman but DeLuca just plays a womanizing maniac that has nothing to do with being a wolfman.
It's shown that Dr Malavaqua is a mad scientist while in the lap and nice while not, and then a moment later he is nice while in the lap.