We should, apparently, think that the Gospel of Peter is a knock-off of Matthew (plus part of Revelation). Quarles summarises the Gospel, then proceeds to dismiss it as fanciful embellishment of accepted canon. He mentions a theory propounded by the Jesus Seminar's John Dominic Crossan:
Although Crossan’s theory has convinced few in the scholarly community, one scholar recently claimed “one can expect that all future research on Gos. Pet. will need to begin with a serious consideration of Crossan’s work” (Paul A. Mirecki, “Gospel of Peter,” ABD 5:278-81, esp. 280). If true, Crossan’s theory would have a devastating effect on confidence in the historical reliability of the accounts of Jesus’ death and resurrection in the four Gospels. According to Crossan’s theory, the sole source for the accounts of Jesus’ death, burial, and resurrection in the four Gospels was a document that was already so laced with legend as to be wholly unreliable even before it reached the hands of Matthew, Mark, Luke, and John. The four Gospels would be unreliable adaptations of an unreliable tradition replete with talking floating crosses and a super-sized Jesus whose head bumped the heavens when he walked out of the tomb!
How much of this is of any consequence? At this stage, with only one more chapter to go, it makes no difference. I've already raised my concern at the editors' decision to place The Question of the Bible at the end of their book; these final chapters do nothing to allay that concern.