'Department [X] would like to recall the message titled '[Mistaken Subject Y]'.You'd like to recall it, would you? I bet you would.
Unfortunately, that's not how email works - you don't get an 'undo' button after you send it, and you don't get to magically delete it from people's computers if you send the wrong thing.
So why don't you just send the obvious message:
'The message [Mistaken Subject Y] was sent in error - please disregard it. My apologies for the confusion.'Ah, because that would imply that someone in particular was to blame, and admin fools can't ever commit that to writing. Let's just press the magic 'recall' button instead!