If an image occurs after some text and it is floated, then in Chrome the image properties dialog will have empty field values and no updates can be made to the image.

Use the HTML below on the demo page and the issue can be seen.

http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx

Sample content
This is some text<img alt="" style="float: right;" src="/aspnet-ajax/Editor/Img/UserDir/Marketing/telerik_125x125_asp.gif" />

Putting an SVG element in the editor content will throw an exception under IE.

Workaround (Make sure to add the script element with the fix right after the RadEditor declaration):

<telerik:RadEditor runat="server" ID="RadEditor1">
    <Content>
        <svg height="100" width="100">
          <circle cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="red" />
        </svg>
    </Content>
</telerik:RadEditor>

<script type="text/javascript">
    var oldMarkListItems = Telerik.Web.UI.Editor.WordListConverter.prototype.markListItems;

    Telerik.Web.UI.Editor.WordListConverter.prototype.markListItems = function(htmlText)
    {
        if (!htmlText)
            return htmlText;

        return oldMarkListItems.call(this, htmlText);
    };
 </script>