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 Inga, Frederick, and Igor reach the secret library, Frederick reaches for the door knob to grasp it with his right hand, but the view from inside the room showing them entering has Frederick's right hand opening the door without using the knob.
Inga: Dr. Fronkensteen! Are you all right?
Fredrick Frankenstein: MY NAME...IS FRANKENSTEIN!
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.