Can I add a link to the node reference when using the autocomplete widget?
This'll do the trick (I've tested it this time ;) ):

foreach($form['field_lessons'][LANGUAGE_NONE] as $key =&gt; $lesson) {
  // If we have a default value for the nid, we have a populated node reference
  if (isset($lesson['nid']) &amp;&amp; is_array($lesson['nid']) &amp;&amp; $lesson['nid']['#default_value'])) {
    // Get the nid
    $nid = $lesson['nid']['#default_value'];

    // Create an edit link
    $link = l('Edit', "node/$nid/edit");

    // Add it to the element
    $form['field_lessons'][LANGUAGE_NONE][$key]['nid']['#suffix'] = $link;
  }
}