http://local.api.com/api/orders/1/notes

# Turn on the rewrite engine
RewriteEngine  on
# If the request doesn't end in .php (Case insensitive) continue processing rules
RewriteCond %{REQUEST_URI} !.php$ [NC]
# If the request doesn't end in a slash continue processing the rules
RewriteCond %{REQUEST_URI} [^/]$
# Rewrite the request with a .php extension. L means this is the 'Last' rule
RewriteRule ^(.*)$ $1.php [L]

$segments = explode('/', trim(parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH), '/'));