Display order of entity reference fields
In case someone stuck on this, i have a solution for Drupal 8 (you can figure it out for 7):
In themename.theme add a preprocess funtion:  

function themename_preprocess_field__field_entity_reference(&amp;$variables) {
    usort($variables['items'], function ($a, $b) {
        $a = isset($a['content']['#node']) ? $a['content']['#node']-&gt;field_display_order-&gt;value : null;
        $b = isset($b['content']['#node']) ? $b['content']['#node']-&gt;field_display_order-&gt;value : null;

        // Do the comparison
        // This &lt;=&gt; operator only work for PHP &gt;= 7
        return $a &lt;=&gt; $b;
    });
}