What are the the five hidden Star Wars characters in Lego Indiana Jones?

In order of appearance and if they are obtainable in story mode. The Lost Temple (Raiders of the Lost Ark) C3PO, Into The Mountains (Raiders of the Lost Ark) Luke Skywalker (story), City of Danger (Raiders of the Lost Ark) Chewbacca, Free the Slaves (Temple of Doom) Leia, Desert Ambush (The Last Crusade) R2D2 (story).