Factual error: The family stays briefly in a British apartment, however the plug sockets displayed are US standard, not UK.
Continuity mistake: When Stewie first discovers Lois and Meg spying through the peephole, the peephole is too high for Stewie to reach, but when Stewie walks up to the peephole, it is low enough for him to look through.
Continuity mistake: When Stewie is golfing and spots Brian in disguise, Stewie has a putter. When Stewie realizes that it is Brian and goes after him he is holding a chipper.
Continuity mistake: When Stewie pushes Brian down the stairs, in the background at the moment he pushes him that the stairs are visible behind Stewie as well.
Continuity mistake: When Peter is giving the team steriods, the syringe always goes back to the same place.
Continuity mistake: When Peter and the rest are at the bar and Quagmire is telling Peter that he looked through his garbage, Quagmire's mug tops up between shots.
Factual error: When Lois, Meg, and Chris go to the stage show on the West End, "theater" is spelled with the Americanism "-er" instead of the UK spelling "-re."
Continuity mistake: When Stewie is playing golf at the top of the stairs before attacking Brian, the layout of the upstairs floor changes quite radically between shots. First Stewie is playing golf with the stairway behind him. Then when Brian puts on the disguise and walks past, there's suddenly a wall behind Stewie. Brian walks off to the left and Stewie begins to chase him that way, but in the next shot Stewie is chasing Brian off to the right. In that same shot you can see that Stewie is running away from the stairs, but in the next shot, without changing direction, he pushes Brian down the stairs, which mysteriously have appeared in front of him.
Continuity mistake: During the scene where the Griffins have Tom Brady over for dinner, when we first see the establishing shot of everyone at the table, Chris is sitting with an empty chair between him and Tom. However, when he asks if he can call him Tom along with Lois and Meg, he is sitting right next to Tom, with no empty chair between the two.
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