Continuation of the Original Series episode Mirror Mirror.
They have Saurian Brandy in the Mirror Universe. The Saurian Brandy bottle, which appeared in several episodes of the original series, appears in this episode in the Mirror Universe's Captain's Cabin, with Kirk taking a swig now and then. The distinctive-shape bottle with red leather straps was actually a modified George Dickel 1964 commemorative edition "powder horn" whisky bottle.
New actor replaces th actor from the first episode as Dr. McCoy.