Not sure how many noticed it, but the Family Guy 100th episode special contained a scene from the upcoming episode (aired directly after). Described by Fox in the press release as:
The FAMILY GUY tribute special celebrates the side-splitting irreverent humor of this fan-favorite animated series by taking a look back at some of the funniest moments, satirical spoofs and music numbers of the past 100 episodes.
You see the Kool-Aid Man breaking down the wall in the courtroom, then slowly backing out realizing the situation. Then, when the 100th episode (Stewie Kills Lois) actually airs, sure enough, this is in there.
I guess this was an obscure joke making fun of special episodes, since the entire thing was somewhat of a spoof considering the interviews with panel participants. Very funny.
I don’t think this was a glitch since Fox put out the press release nearly a month ago (October 8 ) mentioning the order of those episodes. So the order was planned. I think they would have had more than enough time to edit had that not originally been slated to be episode #100.
Anyway, the special was OK, but I’ve never been a fan of those recap, best of, funniest moments, or anniversary episodes on any show. Stewie Kills Lois of course is looking to become a classic (damn cliff hangers).