Broken links?

Every now and then I see in my 404 log following errors:

404 URL: http://paleosmak.pl/www.facebook.com/plugins/like.php?href=http://paleosmak.pl/2014/05/sklad-cukier/&layout=button_count&width=100&height=27&locale=pl_pl&appid=411615338974973

Referred by:

User Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)

I can’t reproduce it, but I keep getting similar errors frequently. Is there a known issue with the plugin that could cause it? Or maybe an interference with some other plugins (async js/wp fastest cache)?

I will be thankful for any comments.

https://wordpress.org/plugins/really-simple-facebook-twitter-share-buttons/

[Moderator Note: No bumping, thank you.]