I don't think any plane in the War had an oh crap dump everything so I don't get shot by an enemy fighter button. -1
The B-17 and B-24 both had an emergency bomb drop system. IIRC on both airplanes it dropped them through the bomb doors -- in the B-17 the door mechanism had a breakaway point that could be reset but in the B-24 it would peel the doors out of the track causing damage and a need to be repaired before return to service.