If any extra-terrestrial elements are in it, I doubt its going to be something on the scale like Close Encounters--it'll probably be more of a downplayed X-Files thing, more mysterious and ambiguous. And before people say that its all silly and unrealistic: have you guys seen any Indy films? Raiders ends with the ark of the covenant being opened, ghosts coming out of it, and lightning bolts from God melting Nazis. Temple of Doom asserts that witchcraft is real and has a man survive his heart being removed during a black magic human sacrifice. Crusade ends with Indy meeting a five-hundred yeard old phantom who restores his father to life with the cup of Jesus Christ himself. Indiana Jones movies have always had an absurdly fantastic element in it somewhere. As long as you don't take it too seriously you will be entertained.