> Ctrl+O in MC will switch to a normal prompt

Better yet! (one-line) shell prompt is always available and has some nifty integrations via <Ctrl+X>. For example, one has a bunch of files visually tagged (selected) on current panel, and wants to tar them up as "/tmp/foo.tgz". Well...

   tar czf /tmp/foo.tgz <Ctrl+X><T>