When Flanders is pretending to be Homer, he actually says, "Annoyed grunt!"--which is how "D'oh!" is always written in the scripts.
"Spil Selv" poster found in Lisa's best friend house or "musik skal der til spil selv" (Danish for "music is going to play for yourself") , refers to a music festival in Copenhagen that took place in the early half of the twentieth century.
Couch gag: Thanos is on the couch and plugs Maggie's pacifier into the Infinity Gauntlet as the fifth Infinity Stone and then all of the Simpsons disintegrate except for Maggie.
Homer texts Lisa during her friend's family recital. While texting her, he uses a popular gif of him retreating into the shrubbery between his and Flanders' house. The gif itself is from Season 5 Episode 16.
According to Marge these are appropriate statements that can be used in dinner conversation:
- Tell me more about that.
- That's really interesting.
- I get my best ideas in the shower.
- I completely agree.