Things  go wrong in radio.  It happens to all of us. It's worse when they go wrong at the beginning of your show, as it then puts you in the wrong mood and things go downhill from there.  

Here, Tony Blackburn kicks off his Top 40 on the 25th May 1980. He's taken the trouble to pre-record the opener, just to make sure it's perfect - but then airs the wrong version....

(Thanks to Richard White)