The Hand That Rocks the Wheelchair - S9-E12
Continuity mistake: When Stewie spots "evil Stewie", the evil clone is off the carpet and next to the hi-fi. In the very next shot he's moved far closer to Stewie and Brian.
The Hand That Rocks the Wheelchair - S9-E12
Continuity mistake: Meg drops Joe's gun into Bonnie's bag at the airport, but it's zipped closed - you hear the baggage check guy unzip it before looking in it.
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