Actually... I think that the parody of 24 will be just that, a parody involved as a subsegment in one of the five episodes that haven't aired yet.
The shrinking/growing Big Bird was hyped as the plotline of the two episode season finale, after the mentioning of the hyped parodies for this season. Just hope it leads to expanding the Number of the Day like the story of Numberella did for the number 21.
And as far as DTF's joke... I kinda get it. It's like that Boy Meets World episode, the high school graduation where the main characters meet a grown-up version of Stuart Minkus again... And he says he's going to go back to "that part" of the school, motioning to the off-screen side. The main chracters say they don't go to that part, cause noone there's ever seen after again.
Hope this helps, and have a good day.