SilverWook said:

Are there any known differences between the broadcasts of ESB and the official audio releases? What appears to be a batch of off air reel to reel recordings has popped up on ebay.

http://www.ebay.com/itm/3-Vintage-STAR-WARS-7-5-7-1-2-Reel-to-Reel-Tapes-EMPIRE-STRIKES-BACK-Lot-/111374771064?pt=Music_Other_Formats&hash=item19ee742378

I've just about reached the end of the internet and can't find any mention one way or another. I will say though (and this means nothing) the published script for the Star Wars NPR has scenes that are not on the my purchased CD set.

Doesn't mean they were ever broadcast, but there were differences. Possible that Empire is the same. That said, it's also 2 hours shorter, so time may not have been an issue.