Index: bp-activity/bp-activity-classes.php
===================================================================
--- bp-activity/bp-activity-classes.php
+++ bp-activity/bp-activity-classes.php
@@ -523,6 +523,10 @@ class BP_Activity_Activity {
 
 				// If we don't have a reference on the parent, put in the root level
 				} else {
+					// Make sure we don't add the current activity ID into the comment tree
+					if ( $d->id == $activity_id )
+						continue;
+
 					$comments[ $d->id ] = $d;
 					$ref[ $d->id ] =& $comments[ $d->id ];
 				}