Continuity mistake: When Stewie is in his room talking to Rupert and himself out loud about Janet we see that Rupert is on the left side of Stewie's pillow. When the camera pans over to Brian who overhears Stewie's musings, after Brian makes fun of Stewie the camera pans back and Rupert is gone. There is also a quick tete-a-tete on the color of Janet's eyes and the final shot is on Stewie and his crib and yet no Rupert to be found. (00:07:20)
Continuity mistake: During the end of Peter's "revised" version of "The King and I" right after the scene where Brian and Peter kung-fu fight, the scene transitions to the next scene where a bunch of girls with bikinis on are surrounding Peter. During the transition, a girl appears out of nowhere. She is blonde and is leaning on Peter. (00:19:10)
Fifteen Minutes of Shame - S2-E12
Other mistake: Right at the end, when Peter takes out the Bible, the front cover is on the wrong side, i.e the back.
I Never Met the Dead Man - S1-E2
Continuity mistake: When Stewie ties the weather control device to the chimney, the black jump-lead is on Stewie's left (HIS left, not our left) and the red one is on his right, but in the next shot, they have switched positions. (00:18:55)
Continuity mistake: When Stewie and Bertram are parachuting down to Earth after the air strike, their parachutes get much closer to each other between shots. This occurs just before they start slapping each other.
Continuity mistake: Peter is playing poker with Lois's father, and he wins. Lois's dad wins. While he's bragging about his son-in-law, look at the table. All the chips and cards are gone.
From Method to Madness - S3-E18
Continuity mistake: When Simon is working with Stewie in his "The Life Cycle" exercise, there are three children behind him: a redhead with freckles, a blonde with glasses, and another blonde. However, after Simon turns around and says, "Any comments?", there is a wide pan of the kids in the class, and the three kids have completely disappeared.
Continuity mistake: When Peter is throwing the disks and then shooting them, you see the door is closed. In the next shot it is open and you can see the inside of the house. Then in the next shot, it is open again. (00:16:10)
The Kiss Seen Around the World - S3-E8
Continuity mistake: When Stewie has kidnapped that bully he holds a weapon in front of the bully's face. When Lois comes in he puts it down, but in a full shot of the room it has disappeared. (00:19:30)
Continuity mistake: When Meg is waiting for Lois outside the hooters, she has a watch on her wrist. When she is talking with Lois, it just disappears after a couple of shots and we don't see it again. (00:11:10)
A Very Special Family Guy Freakin' Christmas - S3-E16
Continuity mistake: When Joe is pretending to have broken his legs, Quagmire is holding Joe's wheelchair with both hands, but in the next shot, he is only holding it with one hand as he has a beer in the other hand. (00:05:45)
Chitty Chitty Death Bang - S1-E3
Continuity mistake: During the scene where Peter is taking Meg away from the cult group, in some shots he is wearing a watch and in others, he isn't. (00:18:40)
Continuity mistake: When Brian says "You can't just ignore these years", the front cover of his magazine is different from how it was in previous shots. (00:14:55)
Continuity mistake: When Lois is showing Stewie the tape in the car, the way she is holding it changes between shots. (00:07:30)
Continuity mistake: When Peter is improvising in the bank, the bag of money disappears in one shot. (00:17:30)
Continuity mistake: When Lois turns on her parents' bedside lamp, it only casts a small beam of light onto the floor, but later in that scene, the same beam of light is much bigger. (00:06:15)
Plot hole: Brian bets Stewie about being at high school for a week. However, this was before Peter's stroke, and before the fire at McBurgertown. It would take at least a few weeks for McBurgertown was rebuilt, then Peter had his stroke, and then Lois tells Chris Peter's stroke was 3 months ago. After this scene, Stewie tells Brian he has lost the bet. However, the bet would only last one week.
And Then There Were Fewer - S9-E1
Continuity mistake: When Muriel Goldman dies, everyone gathers up around her. When that happens, you can see Tom Tacker and Meg in the background, although they both disappeared a few scenes earlier. And than when everyone gathers downstairs, they do a body count and discover Tom and Meg are missing and only then are they found.
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.
Blue Harvest - S6-E1
Continuity mistake: After Vader (Stewie) kills Obi-Wan, Luke yells out and then the shot shows storm troopers firing at him with Vader in the background. Vader's lightsaber is blue, when it should be red. It is red in the previous and next shots. (00:34:00)
Answer: Lacey Chabert was the actress who originally voiced Meg in early episodes. She left of her own accord due to being in school and other acting work; Seth MacFarlane has stated there was no tension with her leaving, but it makes for a handy joke for the show.
Jon Sandys ★