I had similar question, but I found this discussion so won’t send my questions as a new one.
My questions was that is it a SEO (link juice) problem when we did 301 redirects from http://www.example.com/folder to http://www.anotherdomain.com/folder/#rdr=oldsite
We added the hash / parameter to get stats how many visits do we get from the old site now and in the future, and with the help of hash in url we can get this information from our analytics tool.
After reading Mike’s answer, I believe I found my answer and understand that this is not a problem, but if anyone have other comments then please respond. Thanks!