Or retroactive continuity, the alteration of a TV show's history to excise facts inconvenient to the current storyline.
Back in the pilot of the Battlestar Galactica remake aired, there was a scene where Colonel Tigh put a cigar through a picture of his ex-wife, who oddly enough looked exactly like the Cylon spy Dr. Baltar was banging, and who has been spending the rest of the series as Baltar's annoying imaginary friend.
A couple of weeks ago, they had an episode where another copy of Baltar's fantasy girlfriend showed up to accuse him of treason. I found myself asking, "Why is Tigh standing there right next to his ex-wife and not even reacting to her presence?"
But that conundrum was resolved in this week's episode, wherein Tigh's ex-wife comes back. As we see in the "previously" clips, Tigh wasn't burning his cigar through Cylon Chick's picture at all! Our memories — and the recording I made of the pilot — were just faulty, that's all it was.
Do they really think the viewers are so dull-witted that they wouldn't notice? Yes, apparently they do.