Revealing mistake: Peter's right eye overlaps his nose when Lois reminds him about getting drunk off communion wine at church. This mistake was later referenced in "Back to the Pilot." (00:02:50)
Revealing mistake: When Brian asks Peter how much money they're getting from welfare, his neck is drawn over his collar, making his head look like it's disconnected from his body.
Revealing mistake: Peter's right eye overlaps his nose when he's watching TV with his family.
Chitty Chitty Death Bang - S1-E3
Revealing mistake: After the manager of the arcade takes money from other customers and cancels Stewie's reservation, Peter and Chris start walking along a row of arcade machines. Here the background was just copy and pasted over again, as they walk by the same place twice, and start a third time before the scene changes. (00:07:35)
Revealing mistake: Death's right foot disappears when he gets up after he says "You know, my ankle is starting to feel better." (00:21:15)
Revealing mistake: While Lois is unbuttoning her shirt, Death's feet and legs aren't visible on the couch, even though he is lying on it.
Revealing mistake: Einstein's eyes briefly pop out of his head during the Theory of Relativity scene.
I Am Peter, Hear Me Roar - S2-E8
Revealing mistake: When Brian says "Well face it Peter, your attitude towards women isn't exactly enlightened", Brian's dog tag is the same color as his fur. It also stays still, even while Brian is moving his head. (00:11:10)
If I'm Dyin' I'm Lyin' - S2-E9
Revealing mistake: When one of the Gumbels is holding a pencil in his mouth and nodding repeatedly, the shaft of the pencil moves with his mouth, but the tip of the pencil (protruding from his hand) stays still. (00:17:35)
A Picture Is Worth 1,000 Bucks - S2-E11
Revealing mistake: When Brian is shaking his head saying he will never go to the theater with Peter again, you can see part of his neck is missing. (00:09:10)
Revealing mistake: When Brian says "Our tickets were in the bags", half of his left hand is missing for a frame.
There's Something About Paulie - S2-E16
Revealing mistake: At the dealership, when Peter is "flirting" with the first red car, he says, "What's that? You want me inside you?" Just as he's saying "What's that," his right arm clips through the windshield of the car and door, phasing through the car like air. (00:02:15)
He's Too Sexy for His Fat - S2-E17
Revealing mistake: During the scene when the people at the pool think Chris is a car sitting on the diving board, just before Lois moves out of the shot before the scene changes, her lips disappear for a split second. It's really fast but still easy to notice even without pausing or slow motion. (00:07:20)
He's Too Sexy for His Fat - S2-E17
Revealing mistake: In the cutaway scene with the Eskimos, the one calling himself "Jennifer Love Hewitt" starts floating away on a piece of ice towards the camera. Before he actually clears the frame, suddenly he just pops out of existence. (00:14:15)
Revealing mistake: After Peter's encounter with Mayor West, we have the family standing next to the sidewalk in their front yard. Lois walks up holding Stewie, and now you can see there is a perspective error in the animation as next to Lois the mailbox looks comically small, barely big enough to put a stapler in. (00:08:11)
Revealing mistake: When Lois says to become friends with the bullies and earn their trust, she raises her arm. When she does the animation is messed and and he arm merges with the table. (00:10:00)
Death Lives - S3-E6
Revealing mistake: When Peter first meets Lois's dad, when they are talking, when Carter raises his eyebrows, for a split second, you can see his "extra" set of eyebrows.
Revealing mistake: When Peter says "kicking, Lois?", after being kicked into the stereo, his nose very briefly turns white. (00:20:00)
Revealing mistake: When Peter runs across the dock after getting out of the boat, a large chunk of his body is missing.
Suggested correction: It's actually his finger, not his dog tag.
In which case, his tag is missing.
Ssiscool ★
I agree, it's not his thumb because in the next shot of him in the same position, his tag is now there (or colored correctly) and his thumb isn't seen.
Bishop73
It looks like his thumb.