Comment by jw_cook

I also assumed those were going to be links, but after a second of confusion I really liked the side pane with animations. It adds a lot to the article and it's more pleasant than the usual alternatives (lightbox on top of the text, or opening a bunch of tabs).

Off the top of my head, I'm not sure how else you'd visually communicate "this bit is interactive on click/hover but isn't a link." Maybe a different text color (without underline), background color, outline (replaced by the colored highlight bar on hover), or a slightly larger and more distinct icon to replace the generic 'image' icon?