Hi, I recently updated a large multisite installation to 3.8.2, and found that if I enabled the RSS Image Feed plugin I'd have the following issues:
1. sent headers before I could send them from page templates, disabling page template redirects using <?php header('Location: ... '); ?>
2. added two parameters (_wpnonce & _wp_http_referer) to search query strings, resulting in a blank page when you'd search within the WordPress dashboard (Pages, for example). (manually removing _wp_http_referer=..... from the url makes the search work again)
3. when "Add Media" is clicked on a Page, no images are displayed in the popup.
These may be due to specific conflicts between your plugin and other plugins and custom functionality on my multisite. Hopefully this will be helpful as you do continued debugging. Thanks