Here's one I didn't spot during Beta-Testing....
If you go to login with Facebook (for the first time) and if you decide to CANCEL instead of OK when it says "Facebook will share x, y and z with this site"..... then the FB pop-up goes and you get taken to a page on the site you have ES installed on which says:
ERROR: 0 - AN ACTIVE ACCESS TOKEN MUST BE USED TO QUERY INFORMATION ABOUT THE CURRENT USER.