I tightened up the 404 redirection on the templates of an ExpressionEngine site recently and when I next logged into Webmaster Tools for the site, it was reporting a large number of really weird 404 URLs, e.g. /template-group/page-title/1345982934000/ and in some cases /template-group/page-title/1346182913000/1347692092000/
When inspecting those links to find out what page they've been linked from, it shows /template-group/page-title/ so in other words from the correct page URL linking to the incorrect page URL, but when I check the front-end code of those pages, the dodgy links don't exist.
So where do these weird links come from? Has anyone come across something similar before?
Those are timestamps, well apart from the trailing zeros. A quick Google turns up this result - are you using Disqus for comments? If so that's probably the culprit.
Quote from a Google employee on the subject:
It does look like we're picking up something funny via JavaScript there. We're looking into what can be done in this particular case. In the meantime, keep in mind that 404 errors of URLs that are invalid (like these appear to be) are not something that would affect your site's indexing or ranking, so while I understand that they may be confusing (and I'm sorry for the number of URLs here), it's not something that you'd need to take action on.