Here is my .htaccess:
...
rewriterule file%20name.htm http://mysite.com/new_name.htm#anchor [r=301,nc,ne]
...
It's not redirected, and I believe this is because it's not targeting the file with the %20 in the name. As for the flags, I used ne to not rewrite the #anchor portion of the redirect.
Also, the flag "nu" breaks my file and I get internal server 500 error.
Thanks you.