There is an error when using Mootools, because "caption.js" is loaded before mootools.js.

You can change this by doing the following in GoogleAjaxLib.php on line 47:

old:
$headerstuff['scripts']['http://ajax.googleapis.com/ajax/libs/mootools/'.$mootoolsVersion.'/mootools-yui-compressed.js']="text/javascript";

new:
$headerstuff['scripts'] = array('http://ajax.googleapis.com/ajax/libs/mootools/'.$mootoolsVersion.'/mootools-yui-compressed.js' => "text/javascript") + $headerstuff['scripts'];

Regards
delgardo