This is the second episode where Patty and Selma quit smoking and at least one of them relapses. The first was "Opposites A-Frack".
It is revealed that Clancy Bouvier died of lung cancer. In Jazzy and the Pussycats, Homer makes a reference to Clancy Bouvier being dead by saying "I know I will use that white noise machine I got you, when your father died." while he was in bed with Marge.
When Marge tells Homer that Patty will be sleeping on the couch, Homer breaks the fourth wall by saying "But that's where we do our couch gags!" and we then cut to the couch gag seen in the episode.
On Selma's past list of lonely men, Sideshow Bob was there, which was a reference to "Black Widower".
This episode marked the return of Spider-Pig.
Maggie's plan's subtitles also breaks the fourth wall: After securing the perimeter, the ground troops will advance and reinforce flanks, as the aerial units will soften their defenses. Then we shall advance in a pincer moment to infiltrate the compound and liberate our friend. If you've read all of this, congratulations, you're a genius!