Boys Do Cry - S5-E15
Continuity mistake: When Jake plays the piano the music on the sheet changes. Notice the big gap on the sheet which gets smaller. I know the sheet is changed, but the gap still changes.
Continuity mistake: When Peter shocks Chris he is right next to him. In the next shot Peter is further away from Chris.
Factual error: When Peter is sent back to 1984, he plans to see Zapped! in the theater with Lois; Zapped! was released in 1982, and was no longer in theaters by 1984.

Boys Do Cry - S5-E15
Revealing mistake: When Lois places Stewie on the floor whilst at the Little Miss Texas pageant, one of the girls is seen looking at herself in a mirror, only she doesn't seem to have a reflection. (00:15:35)
Boys Do Cry - S5-E15
Other mistake: Towards the very end, they automatically head to the car, planning to leave Texas, without any of their items from the house packed in the car after running away from the mob at the Miss Pageant Contest.
Continuity mistake: All the army men including Brian and Stewie have USA symbols on their arms, but when Stewie and Brian talk to one of them, after they shoot each other in the foot, the USA symbol on the man's sleeve is orange lines and a arrow.
Airport '07 - S5-E12
Other mistake: As Quagmire sits at the bar, Hugh Hefner comes and gives him a pep talk. During it, he says John Holmes said Glen Quagmire is the best pilot. Unless he had seen the news or knew him personally, Hefner couldn't have called Quagmire by name.
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