Trivia

According to Dr. Seuss, the film's creator and co-writer, one of the 150 boys vomited on the piano while filming. This caused a chain reaction and they were left with 150 vomiting boys. Seuss said later that the film's reviews were similar to this incident.

Marilyn Monroe accompanied young Tommy Rettig at the film's premiere.

The words Bart recites while making the blood oath with Mr. Zabladowski are taken word-for-word from the Scout Law of the Boy Scouts of America (trustworthy, loyal, helpful, friendly, etc.).

When Bart and Mr. Zadlabowski are taken to the dungeon via elevator, there is no reference to a third floor dungeon by the Elevator Operator. The third verse of the Elevator Operator's song was cut due to increasingly horrific lyrics referring to household appliances. The complete deleted verse went as follows: "Third floor dungeon, household appliances/Spiked beds, electric chairs/Gas chambers, roasting pots/And scalping devices." (the reference to "gas chambers" was probably regarded to be in bad taste since the film was made so soon after World War II and the Holocaust)

The film's real-world opening sequence is a re-shoot, which was directed by producer Stanley Kramer. As a result, young Tommy Rettig looks and sounds slightly different than he does in the rest of the film. The original version of the scene had a similar structure, but Dr. T. was not Bart's personal piano teacher, he was simply the author of a musical instruction book. In that version, Bart doodles on the picture of Dr. T. on the front of the book, which then comes to life and pulls him into a dream world. Hans Conried was vehemently opposed to the new scene, feeling Kramer was robbing the story of some of its fantasy element by making Dr. T. a real-world character.