In the episode, "Ryan" there is a reference to Hub City which is the home of DC Comics super hero The Question.
Lex shows Ryan his "Warrior Angel" Collection. The cover to "Fantasy Comics-Warrior Angel" #1 is a nod to the cover of DC's "Action Comics" #1 in which Superman made his first appearance.
The floating fortress in the warrior angel comic Clark gives to Ryan is a nod to Clarks eventual fortress of solitude
Clark mentions he has a fear of flying. He'll later go on to adopt flight as part of his power set.