Don't Be a Dickens at Christmas - S16-E9
Continuity mistake: Peter gets Lois a lawn chair. It vanishes from sight when Peter gives Meg her radio.
Crimes and Meg's Demeanor - S16-E8
Continuity mistake: Peter and Meg are in a Greek week. There is a stair close to the front door while we see Peter's drinking. In the next shot, when Peter and Meg are leaving, the stairs disappear.
Crimes and Meg's Demeanor - S16-E8
Continuity mistake: At the beginning of this episode Peter is talking to Meg about her senior year in high school. This makes no sense considering she turned 18 in season 10, which was released in 2012.
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