A FLASHBACK EPISODE REVEALS WHY OLIVER HATES LEX -- As teenagers, Lex (Michael Rosenbaum) and Oliver (Justin Hartley) went to the same prep school, where Oliver and his friends bullied Lex and his friend Duncan (guest star Bryce Hodgson). Lex eventually turned on Duncan to gain their acceptance, prompting Duncan to throw himself off the roof. Lex and Oliver return to the school for a reunion and are startled when Oliver's old pals are killed in violent and mysterious accidents that point to Duncan. Meanwhile, Clark sees satellite photos that show four other craters were created the day he escaped from the Phantom Zone, causing him to believe that others may have followed him. Kristin Kreuk, Erica Durance, Allison Mack, John Glover and Annette O'Toole also star. Steven DeKnight wrote the episode directed by Jeannot Szwarc (#2T7706).