General Zod first appeared in Adventure Comics #283 (April 1961). His full Kryptonian name was Dru-Zod. He also appeared in the first two Superman movies as a military leader and rebel that was banished by Jor-El into the Phantom Zone. He was played by Terence Stamp who supplies the voice of Jor-El in Smallville, including this episode.
The energy burst that hits Martha strongly resembles the one that Clark saw in his nightmare in "Commencement". Upon slowing the video down, you can see the Superman colors of red, blue, and yellow forming the light.
Martha says even when she is gone her love will never die, mirroring what she said about Lara in "Memoria".
Zod technically first appears here, his face being glimpsed, though it was far away and blurry.
Zod is the 25th DC Comics character to be adapted into the series.