Of note, unless my calculations are wrong, this marked the animated debut of green, or actually of any color, kryptonite. It was also shown in some of the New Adventures of Superman episodes that aired with the Adventures of Superboy, but I believe this one debuted first chronologically. The element was first introduced to the mythos via the Superman radio show in 1943 but found its way into the comics in 1949. It was originally supposed to be very rare, arriving as a single meteorite on earth, but as seen in this episode, common criminals or aliens could manage to accumulate bowling balls worth without too much trouble. By the time Smallville came around, kryptonite was about as common as sand.
In spite of the green kryptonite introduction, this episode was a dud. Klaxtor from Zaldir claimed to be from Krypton and to have gained an immunity to kryptonite. He promised to transfer the immunity to Superboy, but instead planned to drain his powers. He failed.
Best Part: I was enjoying the episode until the big twist. Zaldir seemed like a nice enough guy. Besides, if he had a giant kryptonite rock and was evil you would have expected him to just use it to kill Superboy rather than as a ruse to gain his trust.
Worst Part: Superboy expects a lot from his dog. He gave Krypto like two seconds notice that he was in trouble and somehow managed to communicate very specific instructions about melting the master coil of the machine. For some reason, even though the machine didn't work, and even though Superboy didn't know for sure what the machine was supposed to do, he lit up like a Christmas tree and managed to "play along" to find out the alien's plan. Sure he did... Then he tasked Krypto with catching a missile to save the Earth. Good dog indeed.
Episode Count: 0080
Series Count: (03 of 33)