Continuity mistake: After Lois accuses Stewie of peeing on the carpet, he asks her to bend down and slaps her with a glove. The glove remains in his hand in that cut, is still there when there is a wide shot of Peter, Stewie, Lois and Brian (you can just see it next to his trousers in his hand), but when it cuts back to Stewie and he starts on about "the outrages" etc, it is gone (the cut is instant, no time for him to put it back in his pocket). A common error, this one just struck me as strange, because the sandwich Stewie threw at Lois is there the entire scene.
Continuity mistake: In the scene where Lois goes down to the room where Peter is dancing, Peter is wearing blue pants. After he walks over to the door and greets her, he still has blue pants. The next shot of Lois and Peter dancing has him wearing his normal green pants, but after that it goes back to blue pants for the rest of the scene.
Continuity mistake: When Stewie is in the sterile glass cage, Lois is changing his diaper with rubber gloves built into one of the panels (like Homer Simpson's in the opening credits). In previous and subsequent shots, however, the panel is solid glass, with no gloves. (Series 4: The Father, the Son, and the Holy Fonz).
Continuity mistake: When Karen Black is first shown, her blue uniform is sleeveless, showing her white shirtsleeves. After a cut to the "Dawson's Creek" kids, Peter says "It was a movie in the seventies," and Black's outfit has sleeves. Later, when she is helping people off the plane, her uniform once again is sleeveless.
Continuity mistake: When we first see all the guys at the NAAFP meeting, there are two guys in the top right corner; one with a singlet and one with brown hair and a green-brown T-shirt. In the next shot, these two guys come in from the opposite side of the screen.
Continuity mistake: At the bottom of the stairs there is a picture of Peter and Lois, and the song "So Long, Farwell" starts. The kids start singing and you can see in the backround the picture is gone then comes back when the kids are going back up the stairs.
Continuity mistake: Just after Patrick 'kisses' his imaginary girlfriend goodbye and tells Brian to look after her, Brian switches position on the couch. In the first shot he is sitting on a crack between couch pillows, but in the next shot he is sitting in the middle of the centre pillow.
Continuity mistake: In this episode, Mort Goldman shows Peter a dating video he made, saying it's how he and his wife met. He is an adult in the video, yet in an earlier episode 'The Kiss Seen Round The World', Mort's wife tells the Griffins that she met him when they were just 14.
Continuity mistake: When Ulysses S. "Griffin" is chugging beer with Robert E. Lee, Ulysses wins. When he says "How's that Robert E. Lee," he puts the beer glass on his head. After Robert says, "Okay no more slaves, but we still don't have to read books," the glass is in Ulysses' hand. In the next shot it's on his head again.