When creating an external link using the [URL text] wiki markup on Simple Wikipedia, a space is displayed after the link.
Normally this is filled with a blue link icon, however on inspecting the page https://upload.wikimedia.org/wikipedia/en/0/00/Lock_icon_blue.gif (link) presents a 404
In the below image I have highlighted the link and space
I believe to fix this it will end up being a site request? https://en.wikipedia.org/w/skins/Vector/images/external-link-ltr-icon.png (link) appears to be a suitable replacement