diff --git a/activity/activity.class.php b/activity/activity.class.php
index 1fa8ee6..25482ca 100644
--- a/activity/activity.class.php
+++ b/activity/activity.class.php
@@ -65,8 +65,8 @@ function activity_for_assignment( $assignment, $type = "add" ){
         
         groups_record_activity(
             array(
-                'action' => apply_filters( 'courseware_assignment_activity_action', $activity_action, $assignment->ID, $assignment->post_content, &$assignment ),
-                'content' => apply_filters( 'courseware_assignment_activity_content', $activity_content, $assignment->ID, $assignment->post_content, &$assignment ),
+                'action' => apply_filters( 'courseware_assignment_activity_action', $activity_action, $assignment->ID, $assignment->post_content, $assignment ),
+                'content' => apply_filters( 'courseware_assignment_activity_content', $activity_content, $assignment->ID, $assignment->post_content, $assignment ),
                 'primary_link' => apply_filters( 'courseware_assignment_activity_primary_link', "{$primary_link}#post-{$assignment->ID}" ),
                 'type' => "assignment_$type",
                 'item_id' => $bp->groups->current_group->id
@@ -95,8 +95,8 @@ function activity_for_lecture( $lecture, $type = "add" ){
         
         groups_record_activity(
             array(
-                'action' => apply_filters( 'courseware_course_activity_action', $activity_action, $lecture->ID, $lecture->post_content, &$lecture ),
-                'content' => apply_filters( 'courseware_course_activity_content', $activity_content, $lecture->ID, $lecture->post_content, &$lecture ),
+                'action' => apply_filters( 'courseware_course_activity_action', $activity_action, $lecture->ID, $lecture->post_content, $lecture ),
+                'content' => apply_filters( 'courseware_course_activity_content', $activity_content, $lecture->ID, $lecture->post_content, $lecture ),
                 'primary_link' => apply_filters( 'courseware_course_activity_primary_link', "{$primary_link}#post-{$lecture->ID}" ),
                 'type' => "lecture_$type",
                 'item_id' => $bp->groups->current_group->id
@@ -130,8 +130,8 @@ function activity_for_response( $response_data, $type = "add" ){
         
         groups_record_activity(
             array(
-                'action' => apply_filters( 'courseware_response_activity_action', $activity_action, $response->ID, $response->post_content, &$response ),
-                'content' => apply_filters( 'courseware_response_activity_content', $activity_content, $response->ID, $response->post_content, &$response ),
+                'action' => apply_filters( 'courseware_response_activity_action', $activity_action, $response->ID, $response->post_content, $response ),
+                'content' => apply_filters( 'courseware_response_activity_content', $activity_content, $response->ID, $response->post_content, $response ),
                 'primary_link' => apply_filters( 'courseware_response_activity_primary_link', "{$primary_link}#post-{$response->ID}" ),
                 'type' => "response_$type",
                 'item_id' => $bp->groups->current_group->id
diff --git a/courses/courses.class.php b/courses/courses.class.php
index a8907c1..60203e6 100644
--- a/courses/courses.class.php
+++ b/courses/courses.class.php
@@ -325,7 +325,8 @@ function single_course_screen( $vars ) {
         $vars['trail'] = array(
             $course->post_title => $course->permalink
         );
-        return apply_filters( 'courseware_course', &$vars );
+        $vars = apply_filters( 'courseware_course', $vars );
+        return $vars;
     }
     
     /**
diff --git a/groups/groups.class.php b/groups/groups.class.php
index 77070b8..1a43cb9 100644
--- a/groups/groups.class.php
+++ b/groups/groups.class.php
@@ -126,7 +126,7 @@ function screen_handler() {
      * Courseware action to manage group navigation options
      */
     function nav_options() {
-        apply_filters( 'courseware_group_nav_options', &$this->nav_options );
+        $this->nav_options = apply_filters( 'courseware_group_nav_options', $this->nav_options );
         $this->load_template( array(
             'name' => '_nav',
             'nav_options' => $this->nav_options,
@@ -165,9 +165,9 @@ function load_template( $vars = '' ) {
         
         //Exclude internal templates like navigation, starts with an underscore
         if(  substr( $vars['name'], 0, 1) != '_' )
-            apply_filters( 'courseware_group_template', &$vars );
+            $vars = apply_filters( 'courseware_group_template', $vars );
         else
-            apply_filters( 'courseware_template_vars', &$vars );
+            $vars = apply_filters( 'courseware_template_vars', $vars );
         
         if( file_exists( $templates_path . $vars['name']. '.php' ) ) {
             ob_start();