Weird urls showing up in Google database

I am wondering if anyone can point me in the right direction.

In the process of trying to find out why our ranking has dropped we came across links in Google's database like this: http://www.mydomain.com/#!/vietnam (and other destinations) Accessing the links redirects to the home page, which results in us having a bunch of "duplicate" homepages in Google's thinking.

We do have a vietnam resource, but it is set up to be accessed via .../bike_tours/vietnam and it works just fine when accessed through a browser.

Where would a link with the structure ../#!/ come from? And how do I block them from existing or have them return 404s?

Find your nonexistent urls, redirect them to the appropriate pages, and make a specific error page. Sounds like a lot of direct links are erroring, which without a default error page set will default to the home page.

EDIT: The #! on the url appears to possibly be a slider image url or something similar, which would affect the current url. How that's being generated and fed to Google is another question.

We have a 404 error page which shows up for most any malformed url. But any url which starts with a #, & or ? the request redirects to the homepage (ie: ../#whatever or ../&yada or ../?huh)

I tried creating a redirect through htaccess, but .../#!/vietnam still redirects to the homepage.

Discovered the source, it was an external forum widget from MUUT. Their internal links to forum posts start with the /#!/ and since we used base href in the head, all those links were recorded using www.mydomain.com.