Thanks for the bug report.
As you may know we keep the emoticons in a central location under /Data/SiteImages/emoticons rather than the default location which is below the script for the editor. We do this because the path to the editor changes with new versions of the editor and we want to avoid breaking the path to emoticons that may have been used in content as editor versions change over time. So we configure CKeditor to point to our central location for the emoticon images.
It appears that what happened with the latest release of CKeditor is that they changed the names of some of the emoticon files and added some new ones and since these new file names don't exist in our central location they are broken.
The problem is easily fixed by copying the images from /ClientScript/ckeditor434/plugins/smiley/images folder into the folder