Mark Goodacre now has a podcast out which introduces the Gospel of Peter. Towards the end of the podcast, he addresses a unique development in this Gospel. The canonical Gospels never narrate the ascent of Jesus from the grave to heaven (or to the earth, before his ascent to heaven). They only narrate the aftermath, in which women (or women and men) find an empty tomb. Dramatically, the Gospel of Peter adds this scene:
 But in the night in which the Lord’s day dawned, when the soldiers were safeguarding it two by two in every watch, there was a loud voice in heaven;  and they saw that the heavens were opened and that two males who had much radiance had come down from there and come near the sepulcher.  But that stone which had been thrust against the door, having rolled by itself, went a distance off the side; and the sepulcher opened, and both the young men entered.  And so those soldiers, having seen, awakened the centurion and the elders (for they too were present, safeguarding).  And while they were relating what they had seen, again they see three males who have come out from they sepulcher, with the two supporting the other one, and a cross following them,  and the head of the two reaching unto heaven, but that of the one being led out by a hand by them going beyond the heavens.  And they were hearing a voice from the heavens saying, ‘Have you made proclamation to the fallen-asleep?’  And an obeisance was heard from the cross, ‘Yes.’
– The Gospel of Peter (tr. Raymond Brown)
So, as Mark summarises:
“[In the Gospel of Peter,] we have a walking, talking cross and a giant Jesus”
– Mark Goodacre, “NT Pod 55: The Gospel of Peter”, 27 July 2011
But, for Mark’s own interpretation of the Gospel of Peter (discussed here), you will have to wait for NT Pod 56. The burning question is: Will John Dominic Crossan have to start referring to “The Crucified One Gospel”?