diff --git a/src/Entity/Activity.php b/src/Entity/Activity.php
index 0da1ad3b7a..938633c0c2 100644
--- a/src/Entity/Activity.php
+++ b/src/Entity/Activity.php
@@ -187,7 +187,8 @@ class Activity extends Entity
             array_push($target_ids, ...$ids_already_known['additional']);
         }
 
-        return DB::findBy('actor', ['id' => array_unique($target_ids)]);
+        $target_ids = array_unique($target_ids);
+        return $target_ids === [] ? [] : DB::findBy('actor', ['id' => $target_ids]);
     }
 
     public static function schemaDef(): array
diff --git a/src/Entity/Note.php b/src/Entity/Note.php
index 7fa85d9efd..9b24da8fc3 100644
--- a/src/Entity/Note.php
+++ b/src/Entity/Note.php
@@ -350,7 +350,7 @@ class Note extends Entity
     {
         $rendered = null;
         $mentions = [];
-        Event::handle('RenderNoteContent', [$this->getContent(), $this->getContentType(), &$rendered, &$mentions, $this->getActor(), Language::getById($this->getLanguageId())->getLocale()]);
+        Event::handle('RenderNoteContent', [$this->getContent(), $this->getContentType(), &$rendered, $this->getActor(), Language::getById($this->getLanguageId())->getLocale(), &$mentions]);
         $mentioned = [];
         foreach ($mentions as $mention) {
             foreach ($mention['mentioned'] as $m) {