Buffy references Xander's hyena possession in "The Pack".
D'Hoffryn complains that the gang "seduced" Anya into leaving him, "broke" her heart ("Hells Bells") and got her killed ("Chosen").
Despite D'Hoffryn's accusations, it was himself who refused to bring Anya back to her demonic nature and power once she became trapped in the human world, and was eventually forced to start living as one, in "Doppelgangland".
His cynical claims also contradicts his words in "Selfless" ("All good things in time"), when Anya questions him why he spared her life. Apparently, he already knew of her demise.
Buffy references Halfrek's death at D'Hoffryn's hands, also shown in "Selfless".
Xander quotes D'Hoffryn words "Never go for the kill when you can go for the pain," which he listened in episode "Selfless", also repeated in Own It, Part Two.