Do you think that the fourth could have been in that third coffin. The one that didn't open. I know that the fourth was supposedly sealed, but where did his soul go? We know that kyuubi is in Naruto, but where's the fourth? Just because the fourth's soul was sealed doesn't mean that Oro couldn't have unsealed it. Remeber when the third was worried about Naruto (at the beginning when he stole the sacred scroll to learn Kage Bunshin) unsealing kyuubi, that means the fourth could have been unsealed as well. So, two questions:
Who was in that third casket?
Where is the fourth's soul now?