Who was in the third coffin?
When Orochimaru uses his Impure world Summoning technique he summons three coffins and the First and Second Hokage emerge from two of them. Sarutobi then states that he knows who is in the third one and cannot allow him to escape. This leads the viewer to believe that it is probably the Fourth Hokage in the coffin. However it is later stated that a soul sealed by the Reaper death seal cannot be summoned by the Impure world summoning, therefore Minato cannot be the third summoning because he was sealed with the Nine Tailed Fox by the Reaper Death Seal.
The Fourth Hokage was in that coffin, and Orochimaru tried to summon him, but the summoning was incomplete because The Fourth Hokage wasn't in the afterlife, but instead was sealed inside the Death God of the Dead Demon Consuming Seal and that's why even if the Third Hokage didn't stop Orochimaru the summoning wouldn't have been complete. —This unsigned comment was made by Drago1274 (talk • contribs) .