If your URI contains a dot, you'll lose the $_SERVER['PATH_INFO'] variable, when using the built-in webserver.
I wanted to write an API, and use .json ending in the URI-s, but then the framework's routing mechanism broke, and it took a lot of time to discover that the reason behind it was its router relying on $_SERVER['PATH_INFO'].
References:
https://bugs.php.net/bug.php?id=61286