When Peter goes to pick up Meg from the suicidal cult, his watch disappears and reappears in various shots.
When Jennifer turns to Meg to say that they are friends forever, and ever, she has no glasses. Next shot, she has them again.
In this episode, Stewie's birth is shown, and when he is removed from the womb, his head is squashed, like he is normally seen. However, in season 3 episode 19 Stewie's head deformed is explained. Stewie is jumping on the bed and slams his head on the ceiling. If his head was normal at one point in time, it should have also been normal when he first came out.
When Stewie is writing in his journal, in a far shot there is a yellow space ring on his bed spread, but in a close shot there is half a green planet.
When Peter and Chris are leaving Cheesie Charlie's, you can see that all of the arcade machines in the background are the same, even though they're walking away.
Halfway through the episode, while Meg is talking to Jennifer, her glasses disappear and reappear in the same scene.
While Stewie is in Lois' womb he counts his penis as an 11th finger when in fact it should be the 9th because the people in Family Guy only have 8.