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. Not only that, look closely at the picture of Stewie, you will see it has grown. (00:04:20)
Continuity mistake: When the black knight pushes Peter's face into the table, there are cream-coloured serviettes (napkins) laid out, but in the next shot, there are blue serviettes. (00:16:45)
Continuity mistake: During the 'So Long, Farewell' parody, Stewie is seen putting his head on the landing on the stairs, when it cuts back to him, his head is resting on the second stair from the top. (00:04:30)
Continuity mistake: When the children are singing, "So Long, Farewell", as they are going upstairs they pass a picture of Lois' parents hanging along the middle of the stairwell. When they get to the top of the staircase, we see the exact same picture, but now at the head of the stairs. (00:04:20)
Continuity mistake: When Peter has his face pushed onto the table by the black knight, the items on the table change between shots. Easiest to notice is the goblet with jewels. (00:17:40)
Continuity mistake: When Peter is talking Madeline, his mutton join with a bone in it is on the table. Take note of the bone, it points different ways in different shots. (00:17:20)
Continuity mistake: When discussing about Peter becoming a knight, he sits on the sofa. When he does though, his buttons on his shirt keep swapping sides. (00:12:05)
Continuity mistake: At the funeral, Lois can be seen stood right next to Chris in the close up shots, but as Peter goes up to make his speech, Lois has disappeared from shot. (00:08:10)
Continuity mistake: Just as Brian asks what kind of Name Weed is, his plate disappears from in front of him between shots. (00:06:20)
Continuity mistake: Just as Lois says to Peter about him having something to ask Mr. Weed, Mr Weed's fork disappears from his hand. (00:06:05)
Continuity mistake: When the black knight appears and says to Peter "What are you doing with my girl!?", there is a pitcher and a basket with a chicken leg on the table. But on the next shot where the camera is facing to Peter, both the pitcher and the basket disappear. (00:17:20)
Continuity mistake: During the song number when Mr Weed arrives, Stewie has a solo part as he starts to backwards crawl up the stairs. In one shot, he climbs up to the third step, but when the camera changes angles he is only on the second step.
