Random image galleries pull images from other pages on your site, but exclude images if:
- The image is hidden from the gallery page
- The image is on a hidden page
- The image is on a page that is password-protected
If you'd like to exclude other pages' images as well, you can do so by clicking the "asterisk" button at the top-right of a gallery's details page. This will exclude the page's images from being used in random gallery pages.