Alright, after doing some googling, I've figured out how to fix it.
In the GoogleMapAPI.class.php script, change these lines
$_icon_image_path = strpos($iconImage,'http') === 0 ? $iconImage : $_SERVER['DOCUMENT_ROOT'] . $iconImage;
to
$_icon_image_path = strpos($iconImage,'http') === 0 ? $_SERVER['DOCUMENT_ROOT'] .
substr($iconImage,strlen($_SERVER['SERVER_NAME']) + 7) : $_SERVER['DOCUMENT_ROOT'] . $iconImage;
Then do the same for the $_shadow_image_path as well.
This worked for me