According to ComicBook.com on Feb 18, Robert Kirkman, the creator of "The Walking Dead" made an appearance on last night's episode of "Talking Dead". He discussed with Chris Hardwick about the questionable death of Rick Grime's wife Lori.
Kirkman explained to Hardwick that she's just a figment of Rick's imagination, representing a happier time in his life and not an actual ghost. Kirkman also mentions that when Hershel finally hears of Rick's visions, he also could relate since he too has lost his wife and probably had been seeing her her all this time, too.
This was said in jest and Hardwick was baited easily into believing that anyone could possibly be seeing visions of their dead, post apocalyptic loved ones. Though, Kirkman does contend that they now can both relate to each other's losses.
Kevin Smith of AMC's "Comic Book Men" had mentioned previously that there was no body at the scene of Lori's death. The only possible evidence was seeing an over stuffed zombie digesting what could have been her remains.
Kirkman had this to say:
“First, I want to make a joke. Maybe that’s why she’s not a ghost. Huh? What?” Kirkman added, “Are we really saying Carl’s that bad of a shot? I mean do you really think that’s possible that he missed".
So it does stand to reason that a child would probably not be well versed in the human anatomy to succeed in a kill shot. So Kirkman's claim that Lori isn't a ghost could explain that Carl did miss and Lori just crawled away and remaining hidden in the confines of the prison.