For anyone wanting to loop images from another source using Flexslider.
I created a ‘text area’ field type and split the urls with a pipe (|).
www.domain.com/img/01.jpg|www.domain.com/img/02.jpg|www.domain.com/img/03.jpg
<div id="slider" class="flexslider">
<ul class="slides">
<?php
$string = get_field( 'slider' );
$split = explode ( '|', $string );
$split = array_reverse($split);
foreach($split as $img){
echo "<li><img src='{$img}' /></li>";
}
?>
</ul>
</div>
Remove $split = array_reverse($split);
for normal order.