An interesting case of friendly fire... for once reported by the other side:
On 26 January 1944, German-speaking radio operators of 1st Czechoslovak Independent Brigade (fighting on the Eastern Front) were able to intercept Luftwaffe communications and guide the German bombers to destroy German positions and bridge at Ostrozhany that their units had tried to destroy for over one week.
Source:
http://www.czechpatriots.com/csmu/bri-combats5.php