On this page, the JQuery Easing script link is giving a hot-linking message:
http://t3-framework.org/documentation/bs3-customization#back-to-top

I think the documentation needs to be edited to just sent the user to the landing page, not directly to the file.

Also, there are some typos: at Step 2 of the tutorial, it mentions:

"Next, embed the new JS file by defining the file in the assets.xml file in templates/t3_bs3_blank/etc.
<scripts>
<file>js/jquery.ellipsis.js</file>
</scripts>"

This name of the file is incorrect, it should be "jquery.easing.1.3.js"

The suggested CSS for styling mentions a variable:
"background-color: @T3primaryColor;"

That variable is not defined in T3 BS3 framework - I think this is a BS2 variable.

Finally, the arrow icon does not show up using the CSS styling, I think it could be something to do with the FontAwesome icon code, may be this is also incorrect?