A post by jdmorgan has an internal rewrite BEFORE an external redirect? That can only be due to rare and specific circumstances, not applicable to most situations. (The obvious case is when you're rewriting to a php script that will then issue any required redirects or 400-class errors.)
Matter of fact, the <IfModule> envelopes strongly suggest there's other stuff going on. You'd never say this in an htaccess file written for a specific site at a specific time.
Everything ... that is wrong works perfectly fine in FF. In IE10 I get the results above.
Browser variation does point to a cache problem. If you're testing anywhere other than your live site, you can save yourself some aggravation by adding lines such as
ExpiresActive On ExpiresByType text/html "access"
adding extensions as appropriate. Obviously you can't do this on a live site. But if your browser honors the directive, it means that every single time you look at the page, the file will be re-loaded.