Spoiler Carl was pretty defiant and downright mean to his father, tho, considering his age and what he's been thru, I can understand it.
You're right about Michonne's walker double. She was on Talking Dead and more or less said that she looked at the walker and saw herself and decided it was something she did not want to become.
When Rick didn't wake up I started to worry (btw, that poor guy was beaten to sh*t wasn't he?

Damn, he could barely walk/talk)

I could see where Carl would think he "turned" after hearing the moaning noises. Carl couldn't shoot (thankfully) and said to the Walker "come get me."
Nice kind of upbeat ending (so to speak) with the knock on the door, and Rick telling Carl, "It's for you."

Good episode. Still have hopes that baby Judith is with someone and waiting for Carol to show up.