Just noticed this on post #529745 and post #529747, so I'm not sure how widespread it is, but it seems that whatever method is used to convert the source URL of pixiv images into a link to that image's proper pixiv entry doesn't like manga-mode images. For example, the source link for post #529747 should be http://www.pixiv.net/member_illust.php?mode=medium&illust_id=6255644, but ends up as http://www.pixiv.net/member_illust.php?mode=medium&illust_id=1 instead. Is this a known/fixable issue?
Updated by RaisingK