diff --git a/flight/Flight.php b/flight/Flight.php
index 6328db3..6bfc0a7 100644
--- a/flight/Flight.php
+++ b/flight/Flight.php
@@ -206,7 +206,7 @@ class Flight {
      * @return mixed
      */
     public static function get($key) {
-        return self::$vars[$key];
+        return isset(self::$vars[$key]) ? self::$vars[$key] : null;
     }
 
     /**
@@ -216,7 +216,6 @@ class Flight {
      * @param string $value Value
      */
     public static function set($key, $value = null) {
-        // If key is an array, save each key value pair
         if (is_array($key) || is_object($key)) {
             foreach ($key as $k => $v) {
                 self::$vars[$k] = $v;
@@ -273,9 +272,10 @@ class Flight {
         $callback = $router->route($request);
 
         if ($callback !== false) {
+            $params = array_values($router->params);
             self::$dispatcher->execute(
                 $callback,
-                array_values($router->params)
+                $params
             );
         }
         else {
diff --git a/flight/core/Dispatcher.php b/flight/core/Dispatcher.php
index a1ebea9..89b9813 100644
--- a/flight/core/Dispatcher.php
+++ b/flight/core/Dispatcher.php
@@ -71,7 +71,7 @@ class Dispatcher {
      * @param callback $callback Callback function
      */
     public function get($name) {
-        return $this->events[$name];
+        return isset($this->events[$name]) ? $this->events[$name] : null;
     }
 
     /**
diff --git a/flight/net/Request.php b/flight/net/Request.php
index 6177495..6db99f8 100644
--- a/flight/net/Request.php
+++ b/flight/net/Request.php
@@ -45,14 +45,14 @@ class Request {
                 'url' => $_SERVER['REQUEST_URI'],
                 'base' => str_replace('\\', '/', dirname($_SERVER['SCRIPT_NAME'])),
                 'method' => $_SERVER['REQUEST_METHOD'],
-                'referrer' => $_SERVER['HTTP_REFERER'],
+                'referrer' => isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '',
                 'ip' => $_SERVER['REMOTE_ADDR'],
-                'ajax' => ($_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest'),
+                'ajax' => isset($_SERVER['HTTP_X_REQUESTED_WITH']) ? ($_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest') : false,
                 'scheme' => $_SERVER['SERVER_PROTOCOL'],
                 'user_agent' => $_SERVER['HTTP_USER_AGENT'],
                 'body' => file_get_contents('php://input'),
-                'type' => $_SERVER['CONTENT_TYPE'],
-                'length' => $_SERVER['CONTENT_LENGTH'],
+                'type' => isset($_SERVER['CONTENT_TYPE']) ? $_SERVER['CONTENT_TYPE'] : '',
+                'length' => isset($_SERVER['CONTENT_LENGTH']) ? $_SERVER['CONTENT_LENGTH'] : 0,
                 'query' => new Collection($_GET),
                 'data' => new Collection($_POST),
                 'cookies' => new Collection($_COOKIE),
diff --git a/flight/net/Response.php b/flight/net/Response.php
index 1da1ad5..23a7965 100644
--- a/flight/net/Response.php
+++ b/flight/net/Response.php
@@ -151,7 +151,9 @@ class Response {
      * Sends the response and exits the program.
      */
     public function send() {
-        ob_end_clean();
+        if (ob_get_length() > 0) {
+            ob_end_clean();
+        }
 
         if (!headers_sent()) {
             foreach ($this->headers as $field => $value) {
diff --git a/flight/net/Router.php b/flight/net/Router.php
index 4115758..5b3a492 100644
--- a/flight/net/Router.php
+++ b/flight/net/Router.php
@@ -58,9 +58,9 @@ class Router {
      * @param callback $callback Callback function
      */
     public function map($pattern, $callback) {
-        list($method, $url) = explode(' ', trim($pattern), 2);
+        if (strpos($pattern, ' ') !== false) {
+            list($method, $url) = explode(' ', trim($pattern), 2);
 
-        if (!is_null($url)) {
             foreach (explode('|', $method) as $value) {
                 $this->routes[$value][$url] = $callback;
             }
@@ -85,7 +85,7 @@ class Router {
                 if ($str == '*') {
                     $str = '(.*)';
                 }
-                else if ($str{0} == '@') {
+                else if ($str != null && $str{0} == '@') {
                     if (preg_match('/@(\w+)(\:([^\/]*))?/', $str, $matches)) {
                         $ids[$matches[1]] = true;
                         return '(?P<'.$matches[1].'>'.(isset($matches[3]) ? $matches[3] : '[^(\/|\?)]+').')';
@@ -120,7 +120,8 @@ class Router {
         $this->matched = null;
         $this->params = array();
 
-        $routes = ($this->routes[$request->method] ?: array()) + ($this->routes['*'] ?: array());
+        $routes = isset($this->routes[$request->method]) ? $this->routes[$request->method] : array();
+        if (isset($this->routes['*'])) $routes += $this->routes['*'];
 
         foreach ($routes as $pattern => $callback) {
             if ($pattern === '*' || $request->url === $pattern || self::match($pattern, $request->url)) {
diff --git a/flight/util/Collection.php b/flight/util/Collection.php
index 85d86bc..eae2b28 100644
--- a/flight/util/Collection.php
+++ b/flight/util/Collection.php
@@ -36,7 +36,7 @@ class Collection implements \ArrayAccess, \Iterator, \Countable {
      * @return mixed Value
      */
     public function __get($key) {
-        return $this->data[$key];
+        return isset($this->data[$key]) ? $this->data[$key] : null;
     }
 
     /**