When Peter beats Andy at darts Cleveland is seen holding a mug of beer but when Andy's wife enters the bar, Cleveland has a glass of milk.
When the family is at the table. Peter drinks milk and then they go to Stewie. Stewie is cutting brown meat and seems to have mashed potatoes or something. After the angle changes, there is red-pink meat, which hasn't been cut, with what looks spinach.
When Meg turns to Neil at her locker, the top of her boots change colors from orange to yellow and then back.
During the football game, the ball receiver is clearly African American, but his hands are white before he grabs the ball. Once he grabs the ball and turns, his hands instantly turn to his skin color.
After Meg is hit by the lunch meat, Peter is still holding his hot dog. The meat was originally white, but when the hot dog is lifted in the "ready-to-throw" position, the meat turns brown.
When Meg is performing her act, the blonde girl next to her doesn't have a big butt. However, when the scene cuts back to her, she has a big butt again from then and towards the scene where Peter throws the hot dog at Meg.