In the middle of the episode, Abraham jumps out of the (driven by Sasha) and kills a walker and when he gets back into the car he is covered in blood. However, in the final moments of the episode he looks out the back window and when he turns back, there is no blood on him.
The position of Carter's body changes within about 10 seconds. At first, he is completely on his right side and shortly after when Rick stands up, Carter is on his back.
When Rick had Carter on his hands and knees and decides not to kill him, you can hear the sound of a hammer being decocked. The gun he is holding is a Glock, which is striker fired and therefore has no hammer to make that sound.
When the walkers are being directed by the fence to the right at the corner of Redding Rd & Marshall Rd the same walkers can be seen close up to the left of the street signs and further down the road to the right of the street signs. Specifically a white woman in a white top and dark blouse and dark hair can be seen with her right arm dangling out to the right side in both instances.
A 2012 Toyota Prius v is shown, the apocalypse happened in 2010.
When the tractor trailer in the quarry falls off the cliff, you hear it exactly as it is happening instead of a delay because of the distance.
Instead of moving the quarry walkers closer to Alexandria, they could just be directed over the cliff. As seen later, their skulls explode simply by walking into barriers. Since they are distracted by almost anything (and may migrate), there is nothing to stop the horde (once paraded miles away) from reversing their course and heading right back toward Alexandria, anyway.