When Rick gets into the van in the opening scene, the little triangle window by the side mirror is broken off. In the next shot from inside the van, it's fixed.
When Rick slides the pistol onto the cross on Carl's grave, it was seen that it was slid almost to the middle where the vertical and horizontal meet. In the next scene, the pistol is literally inches from the end of the left horizontal section of the cross.
When Rick and Michonne are fighting their way out of the trash pile walkers, one of the background walkers brushes the dirt off of her pants leg as she stands up.