Not trying to play a certain sound we don't have yet.

app/templates/common/table.jade

@@ -16,6 +16,8 @@ table.table
   block tableBody
     for document in documents
       - var data = document.attributes;
+      - if(data.slug == 'ace-of-coders' && new Date() < new Date(1441954800000))
+      -   continue;
       tr(class=document.getOwner() == me.id ? 'mine' : '')
         td
           a(href="/editor/#{page}/#{data.slug || data._id}")

app/views/clans/ClanDetailsView.coffee

@@ -191,6 +191,7 @@ module.exports = class ClanDetailsView extends RootView
         name: utils.i18n(campaign.attributes, 'fullName') or utils.i18n(campaign.attributes, 'name')
         levels: []
       for levelID, level of campaign.get('levels')
+        continue if level.slug is 'ace-of-coders' and new Date() < new Date(1441954800000)
         campaignLevelProgression.levels.push
           ID: levelID
           slug: level.slug
@@ -198,7 +199,7 @@ module.exports = class ClanDetailsView extends RootView
         if level.concepts?
           for concept in level.concepts
             @conceptsProgression.push concept unless concept in @conceptsProgression
-        if level.type == 'hero-ladder'
+        if level.type is 'hero-ladder'
           @arenas.push level
       @campaignLevelProgressions.push campaignLevelProgression
     @render?()

app/views/play/level/LevelPlaybackView.coffee

@@ -286,7 +286,8 @@ module.exports = class LevelPlaybackView extends CocoView
         @scrubTo ui.value / @sliderIncrements
         if ratioChange = @getScrubRatio() - oldRatio
           sound = "playback-scrub-slide-#{if ratioChange > 0 then 'forward' else 'back'}-#{@slideCount % 3}"
-          Backbone.Mediator.publish 'audio-player:play-sound', trigger: sound, volume: Math.min 1, Math.abs ratioChange * 50
+          unless /back/.test sound  # We don't have the back sounds in yet: http://discourse.codecombat.com/t/bug-some-mp3-lost/4830
+            Backbone.Mediator.publish 'audio-player:play-sound', trigger: sound, volume: Math.min 1, Math.abs ratioChange * 50
 
       start: (event, ui) =>
         return if @shouldIgnore()