           <p>These images will be uploaded during after last step of this process, which could take a long time depending on how many you select. Make sure you’ve got a steady internet connection. You’ll have an opportunity to review and refine your selection here before continuing.</p>
 
           {for manifestFilename of wizardData.manifests
-            <span>
+            <span key={manifestFilename}>
               {manifestFilename}
               <button onClick={@removeManifest.bind this, manifestFilename}>&times;</button>
               &emsp;

      <tr key={filenames.join()}>
        <td>
          {for filename, i in filenames
            <div>
              {filename}
              {unless files[i]?
                <span className="form-help error" title="Missing image">&nbsp;<i className="fa fa-exclamation-circle"></i></span>}

        </td>

        {for column in MANIFEST_COLUMNS[1...]
          <td key={column}>{metadata?[column] ? <span className="form-help">?</span>}</td>}

        <td>
          <button onClick={@removeSubjects.bind this, filenames...}>&times;</button>
