Which details of Offred's account does Professor Pieixoto interpret incorrectly?

In the "Historical Notes," Pieixoto states that: "there was little that was truly original with or indigenous to Gilead" (382). Pieixoto gives several examples of where Gileadian got the ideas for certain practices in the regime. For instance, he says that the collective rape ceremony came from an English village custom of the seventeenth century (382). By asserting that the events in the novel are similar to events that have actually occurred, Atwood encourages readers to recognize and respond to the injustices that human beings commit. Pieixoto is saying that he can trace elements of Offred's account to other parts of history thereby making Offred's story somehow fictional rather than real.

There is a fantastic article that looks at the inner workings of the epilogue; parts of the article come from a review with Atwood herself. The Professor does a lot of his own interpreting in this section. I am going to put in a short excerpt here and will link the article in the sources below. I think you will find everything you need there.......... it's a fascinating look at Atwood and the novel.

"In a parallel to Gilead’s obsession with controlling the appearance of things within the regime, Pieixoto attempts to control Offred’s narrative and how readers interpret it. He is responsible for placing Offred’s non-linear, oral narrative into the order in which readers find it, raising questions about the extent to which readers should trust the voice of narration throughout the novel, since Offred’s voice is literally mediated, if not subsumed, by Pieixoto’s throughout. Consequently, Atwood implicitly reminds and warns readers about the power of editing, since the originally oral version of Offred’s story is subject to editing and is therefore no more inherently truthful or accurate than are the carefully crafted visual scenes created and employed by Gilead."