In Season 2, as the group is killing the walkers coming out of Hershel's barn, the Walkers on the ground seem to shift, going from scattered about, to forming a pile, to making a path for Walker Sophia to get through.
2. Baby Judith Doesn't Age
The continuity with Judith's age isn't kept up. She appears the same age when the prison fell and when they arrived.
3. We See You
When Daryl is with his "Claimed" group, they find an auto shop. A crew member in an orange vest is visible in the reflection of the window.