We mentioned that Tiresias appears in The Odyssey in class, and I looked up the reference (it's on lines 100-172, Book XI in the Fagles translation). I didn't know, however, that Oedipus himself also makes an appearance in the same scene in the underworld, on lines 307-313:
"And I saw the mother of Oedipus, beautiful Epicaste [Jocasta?].
What a monstrous thing she did, in all innocence--
she married her own son...
who'd killed his father, then he married her!
But the gods soon made it known to all mankind.
So he in growing pain ruled on in beloved Thebes"
The Odyssey dates to around 700 B.C., and Oedipus Tyrannos to 429 B.C., so clearly this was an old legend. I wonder if Sophocles himself changed the ending of the story to make it more of a tragedy, or if Homer just had a different version of the myth.