(Sorry if ResourceLoader isn't the right component for this.)
In RTL wikis, the icon displayed next to external links (with the class .external) is backwards for browsers that support data URIs. (That is, it's displaying the same image as is displayed for LTR wikis.)
The CSS code does have the correct image (skins/Vector/images/external-link-rtl-icon.png) in the code within the ordinary url(//bits.wikimedia...), but the embedded version isn't actually of that image. Instead, it's embedding skins/Vector/images/external-link-ltr-icon.png .