Audio problem: When they first find the monster conscious, Frederick says "Is the sedative ready?" The reply, "Yes, doctor," comes from Frau Blucher, who isn't there, and doesn't make another appearance in the film until she releases the monster and he escapes. It should've been either Inga or Igor saying it.
Suggested correction: I thought it was supposed to be Inga.
Continuity mistake: Inspector Kemp is known in the village to have had his right arm to be prosthetic (supposedly torn off by the original monster), but during the searching in the woods scene, after the riot starts, when he signals the villagers to keep quiet, his LEFT arm is suddenly prosthetic. The entire shot was apparently made of the villagers moving from left to right, but the negative was threaded backwards to get them to move from right to left. The Inspector's eyepatch is also on the wrong eye, and a villager is holding his shotgun left-handed (shown at the town gathering at the start of the riot as being right-handed).
Suggested correction: It's a running gag: Igor's hump changes sides, Kemp's missing arm and eye change sides.
Except that for the whole movie every time Inspector Kemp uses his right arm it keeps making a sound to indicate that it's fake, but he can move his left arm normally, showing that it's his real arm. Not only that but, the moving hump was Marty Feldman's idea. It can't actually be confirmed that Inspector Kemp's prosthetic right being switched to the left for that one scene was part of the gag or not.
Character mistake: When Herr Falkstein introduces himself to Frederick he tells him he has come 5,000 miles to bring him his great-grandfather's will. The ancestor in question was supposed to be his grandfather, not great-grandfather. (00:11:53)
Suggested correction: Victor is Fredrick's grandfather, but not the one who died. Baron Beaufort von Frankenstein died, leaving the estate to Fredrick. Beaufort is his great grandfather.
