The images in https://mathoverflow.net/a/123671/3 are not displaying properly (checked in Chrome and Firefox), but I'm not sure why. Loading the given URLs in a new tab works fine.
I suppose the problem which was suggested by Stephan Kohl, i.e. missing extension. I suggested an edit which changed the links from links like http://www.freeimagehosting.net/ta8ni to links to the actual png picture: http://www.freeimagehosting.net/newuploads/ta8ni.png . The post seems to be fine after this edit.
My personal opinion is that it would be better to upload the picture using imgur, since this would make the link more durable and prevent link rot. (Images uploaded via imgur should exist indefininetely, at least in theory.) But I leave this to the OP (or other people willing edit the post further).