In a recent podcast show from Michael Rosenbaum Jensen Ackles said that his character ( Jason Teague) was supposed to be in season 5 but got an offer to star in Supernatural, he accepted.
There is a mention at the end on Sam Loeb, son of the writer-producer of Smallville Jeph Loeb. Loeb's son, Sam, died on June 17, 2005 at the age of 17, after a three-year battle with bone cancer. In 2006, Sam's final work appeared in Superman/Batman #26, which was nearly completed before his death.
Fortress of solitude is seen for the first time which becomes the occasional headquarters for Clark Kent/Superman.
This marks the first time where Erica Durance gets a mention in the opening credits. Previously she was given the billing of a guest star.
First appearance of Aethyr and Nam-Ek both disciples of Zod, who is a ruthless and powerful Kryptonian military leader and a recurring antagonist.