Other mistake: When Peter and Lois begin to search for the black market, it then cuts to an exterior shot of Stewie's daycare. In this shot, not only is the entire left side of the chain link fence missing, but bizarrely, this missing gate still casts a shadow on the sidewalk. (00:18:40)
Other mistake: After the Kentucky cut away with Peter, we're back on the plane. He sits down and is surrounded by the exact same other characters from the last plane we saw him on: the pink lady sitting next to him and the man in the green suit sitting behind him. This is after at least a day or two in the episode, and Peter is flying all over the world on different planes as a freeloader with his wife's new job. It's next to impossible that he'd be sitting next to the same lady and in front of the same man again. (00:09:30 - 00:15:10)
Other mistake: This mistake appears to only be in the digital version of the episode on Hulu and Disney+. After Stewie fires the net gun at the other kid in the Duck Duck Goose game and says he's still it, we get our first real look at Janet as she giggles at Stewie. For a few frames as it zooms in on her, the top of her head is cut off and blinks out of existence. (00:05:55)
Other mistake: While Lois is kneeling at the entrance of the playground with Stewie, a woman is walking by carrying a baby. The playground gate entrance is casting a long shadow; however, Lois, Stewie, and the woman are not casting shadows in the same way. (00:03:35)
Chosen answer: It's a real song called "Elvira". Originally by Dallas Fraizer in '66, however, this version seems to be the Oak Ridge Boys cover version. However, the mega lesbians skip the verse and just sing the chorus after the opening line.
Bishop73