1x12 - The Adventures of Superboy

When a friend of Clark's finds a magical cape he is sent back in time to Camelot. Clark as Superboy goes back in time to help his friend. Superboy saves him from being trampled by the Black Knight, but is soon forced to duel the Black Knight who is being helped by Merlin. Superboy wins and the Black Knight and Merlin are arrested by King Arthur. Superboy and his friend return to the their own time.