Error copying fields from node to tab

I'm copying fields of a node to a tab created in that node in page.tpl.php (copying, because the info in that field needs to be in both places). Here is the code:

    if( !empty( $nodeRef[$field] ) ) {
      $render_array[$field] = $nodeRef[$field];
    }

(where $nodeRef = &$data['content']['system_main']['nodes'][$nid];, $field is the name of the field and $render_array is the value for 'contents' when calling quicktabs_build_quicktabs(). )
This works fine, except for an error caused by the #object key of a field, 'Uncaught exception thrown in session handler.' The #object key is undocumented; I don't know what it refers to. The error can be fixed with unset($render_array[$field]['#object']);
However, I have no idea if unsetting the #object key has any potentially bad side-effects. Does anyone know if this is safe?
Also, does anyone know what the #object key in a Field render array refer to, and what is the purpose of including this?