Plot hole: Kemp, after visiting the castle, would've assured the people that Dr. F. Was not making a monster. So, why is that guy boarding up his house if he has no evidence that a monster even exists? Even if he did tell them that he believes that Dr. F. Was creating a monster, how did the guy know that it had escaped? Also, he says that he remembers the last time. He wasn't old enough to remember something that someone else's grandfather did.
Young Frankenstein (1974)
1 plot hole - chronological order
Directed by: Mel Brooks
Starring: Peter Boyle, Gene Wilder, Teri Garr, Madeline Kahn, Marty Feldman
Continuity mistake: When Dr. Frankenstein introduces himself to the monster with a soothing "Hello, there", his right hand is on the restraint over the monster's chest. The next shot shows the doctor placing his hand on the restraint again.
Dr. Frederick Frankenstein: You know, I'm a rather brilliant surgeon. Perhaps I can help you with that hump.
Igor: What hump?
Trivia: When the Burgermeister says the village and townspeople were terrorized "five times before", it is a reference to incidents from five Frankenstein films: Frankenstein, Bride of Frankenstein, Son of Frankenstein, Ghost of Frankenstein, and House of Frankenstein.
More questions & answers from Young Frankenstein
Answer: She most likely missed Frederick and wanted to be with him.