diff --git a/externs/mediakeys.js b/externs/mediakeys.js
index 8183a3175a..100f203da0 100644
--- a/externs/mediakeys.js
+++ b/externs/mediakeys.js
@@ -114,8 +114,8 @@ MediaKeyStatusMap.prototype.entries = function() {};
 
 
 /**
- * The functor is called with each value.
- * @param {function(string)} fn
+ * The functor is called with each value and key.
+ * @param {function(string, BufferSource)} fn
  */
 MediaKeyStatusMap.prototype.forEach = function(fn) {};
 
diff --git a/lib/player/stats.js b/lib/player/stats.js
index 160c499010..f565c6c072 100644
--- a/lib/player/stats.js
+++ b/lib/player/stats.js
@@ -97,7 +97,7 @@ shaka.player.Stats = function() {
    * Bandwidth history.  Each timestamped value is a bandwidth measurement, in
    * bits per second.
    *
-   * @type {!Array.<shaka.player.Stats.TimedValue.<number>>}
+   * @type {!Array.<!shaka.player.Stats.TimedValue.<number>>}
    * @expose
    */
   this.bandwidthHistory = [];
@@ -106,8 +106,8 @@ shaka.player.Stats = function() {
    * StreamInfo history.  Each timestamped value is a stream chosen
    * by the player.
    *
-   * @type {!Array.<shaka.player.Stats.TimedValue.<
-   *            shaka.player.Stats.StreamStats>>}
+   * @type {!Array.<!shaka.player.Stats.TimedValue.<
+   *            !shaka.player.Stats.StreamStats>>}
    * @expose
    */
   this.streamHistory = [];
diff --git a/lib/polyfill/patchedmediakeys_20140218.js b/lib/polyfill/patchedmediakeys_20140218.js
index a4326fcd3a..65fe081a51 100644
--- a/lib/polyfill/patchedmediakeys_20140218.js
+++ b/lib/polyfill/patchedmediakeys_20140218.js
@@ -781,10 +781,7 @@ shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
 };
 
 
-/**
- * Array entry 0 is the key, 1 is the value.
- * @return {Iterator.<Array.<!BufferSource|string>>}
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
     entries = function() {
   var fakeKeyId =
@@ -798,22 +795,18 @@ shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
 };
 
 
-/**
- * The functor is called with each value.
- * @param {function(string)} fn
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
     forEach = function(fn) {
   if (this.status_) {
-    fn(this.status_);
+    var fakeKeyId =
+        shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.KEY_ID_;
+    fn(this.status_, fakeKeyId);
   }
 };
 
 
-/**
- * @param {!BufferSource} keyId
- * @return {string|undefined}
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
     get = function(keyId) {
   if (this.has(keyId)) {
@@ -823,10 +816,7 @@ shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
 };
 
 
-/**
- * @param {!BufferSource} keyId
- * @return {boolean}
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
     has = function(keyId) {
   var fakeKeyId =
@@ -839,9 +829,7 @@ shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
 };
 
 
-/**
- * @return {Iterator.<!BufferSource>}
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
     keys = function() {
   var fakeKeyId =
@@ -855,9 +843,7 @@ shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
 };
 
 
-/**
- * @return {Iterator.<string>}
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeyStatusMap.prototype.
     values = function() {
   /** @type {!Array.<string>} */
diff --git a/lib/polyfill/patchedmediakeys_v01b.js b/lib/polyfill/patchedmediakeys_v01b.js
index 71c1daa0b6..60fdfa6bfb 100644
--- a/lib/polyfill/patchedmediakeys_v01b.js
+++ b/lib/polyfill/patchedmediakeys_v01b.js
@@ -133,9 +133,8 @@ shaka.polyfill.PatchedMediaKeys.v01b.setMediaKeys = function(mediaKeys) {
  */
 shaka.polyfill.PatchedMediaKeys.v01b.getVideoElement_ = function() {
   var videos = document.getElementsByTagName('video');
-  /** @type {!HTMLVideoElement} */
   var tmpVideo = videos.length ? videos[0] : document.createElement('video');
-  return tmpVideo;
+  return /** @type {!HTMLVideoElement} */(tmpVideo);
 };
 
 
@@ -923,10 +922,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.getStatus =
 };
 
 
-/**
- * Array entry 0 is the key, 1 is the value.
- * @override
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.entries =
     function() {
   var fakeKeyId =
@@ -940,22 +936,18 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.entries =
 };
 
 
-/**
- * The functor is called with each value.
- * @param {function(string)} fn
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.forEach =
     function(fn) {
   if (this.status_) {
-    fn(this.status_);
+    var fakeKeyId =
+        shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.KEY_ID_;
+    fn(this.status_, fakeKeyId);
   }
 };
 
 
-/**
- * @param {BufferSource} keyId
- * @return {string|undefined}
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.get =
     function(keyId) {
   if (this.has(keyId)) {
@@ -965,10 +957,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.get =
 };
 
 
-/**
- * @param {BufferSource} keyId
- * @return {boolean}
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.has =
     function(keyId) {
   var fakeKeyId =
@@ -981,9 +970,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.has =
 };
 
 
-/**
- * @override
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.keys =
     function() {
   var fakeKeyId =
@@ -997,9 +984,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.keys =
 };
 
 
-/**
- * @override
- */
+/** @override */
 shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.prototype.values =
     function() {
   /** @type {!Array.<string>} */
diff --git a/lib/polyfill/promise.js b/lib/polyfill/promise.js
index aa489c402f..5aba2ae0be 100644
--- a/lib/polyfill/promise.js
+++ b/lib/polyfill/promise.js
@@ -62,7 +62,12 @@ shaka.polyfill.Promise = function(opt_callback) {
 };
 
 
-/** @typedef {{ promise: !shaka.polyfill.Promise, callback: function(*) }} */
+/**
+ * @typedef {{
+ *   promise: !shaka.polyfill.Promise,
+ *   callback: (function(*)|undefined)
+ * }}
+ */
 shaka.polyfill.Promise.Child;
 
 
diff --git a/lib/util/content_database.js b/lib/util/content_database.js
index 19130d2a1c..83f190a730 100644
--- a/lib/util/content_database.js
+++ b/lib/util/content_database.js
@@ -125,9 +125,8 @@ shaka.util.ContentDatabase.StreamIndex;
 
 /**
  * @typedef {{
- *    index: number,
  *    start_time: number,
- *    end_time: number,
+ *    end_time: ?number,
  *    start_byte: number,
  *    url: string
  *  }}