- Eugene Lipinski as Mr. Mortman
- Deborah Scorsone as Lucy Dark
- Christopher Tuah as Aaron
- Lynne Cormack as Mrs. Dark
- Dan Lett as Mr. Dark
- Brandon Bone as Randy Dark
Lucy loves telling monster stories, but her family and friends are tired of her wild tales. So when Lucy sees a real monster—Mr. Mortman, the local librarian—no one will believe her. If she can just get proof that he is a monster maybe then they'll listen. But is it too late? Mom and dad have invited Mr. Mortman to dinner! This is sure to be one meal that'll be hard to swallow.
Differences from the book
- In the book, Mr. Mortman keeps pet turtles, but in the episode, he keeps pet spiders.
- The scene where Lucy goes to Aaron's house and meets his brother is not depicted in the episode.
- The scene where Lucy and Aaron follow Mr. Mortman home is not depicted in the episode.
- Unlike the book which ended with Mr. Mortman being eaten by Mr. and Mrs. Dark's monster forms, the ending is extended where Mr. and Mrs. Dark explain that Mr. Mortman is the first monster to come into their town in 20 years besides them where they don't want their children to tell anybody else. When Aaron appears with a monster mask and later takes it off when Mr. and Mrs. Dark had brought out their fangs, he asks what is for dessert. Mr. Dark then answers with, "You....like Cherry Pie?" and the family laughs. Lucy and Randy are never seen as monsters.
- In the book, Mr. Mortman mainly eats flies. However, in the episode, he eats crickets instead.
|Title||Release date||Media type|
The Girl Who Cried Monster & The Cuckoo Clock of Doom (Spanish)
|September 16, 2008||DVD|
|August 26, 2014||DVD|
- This episode, along with "The Cuckoo Clock of Doom", on their original premieres, had a special opening theme in which there was a ten-second remix when R.L. Stine is walking through the grass with the briefcase. When the G passes the dog, that part of the music is played with a different instrument. There were also different scenes from the television show, when the door opened.
- Mr. Mortman's actor, Eugene Lipinski, later voiced Rocky in "Night of the Living Dummy III".
- The music Mr. Mortman hums is none other than the famous song A Little Night Music.