We have a Facebook app that includes web intents integration to award bonus points when users tweet about their performance. The app runs with no problem in all browsers outside of Facebook and in all browsers except IE9 when run within Facebook. The issue seems to stem from the way Facebook runs the code within an iframe.
The specific error we are seeing occurs during page load in hubclient.js (line 7): Unable to get value of the property insertBefore.
The code is integrated into our app based on https://dev.twitter.com/docs/intents/events