I tried this, the my founding is interesting.
I made some error in a controler code intentionally, so rails will produce a 500 Error page. When I run it in development mode, both mongrel and litespeed return 500 page, however, when I switch to production mode, rails return a page with 200, for both mongrel and litespeed, seems the old controler code without the error was used.
It is a rails issue I think.