This article highlights seven intriguing facts about the TV show NCIS that every loyal fan should be aware of. These facts include Mark Harmon's real-life marine background, the initial inspiration behind the show, the inclusion of real-life marines as background actors, and the extensive research conducted by the show's writers. Additionally, the article discusses the cast's close bond and harmonious working environment, the real-life consequences faced by actors for breaking NCIS rules on set, and the show's ongoing success and longevity.