Complete theory about Gleen's death escape.
Before reading understand that this post is based only on assumptions and merger of existing theories.
As we saw in the last episode Nicholas allegedly committed suicide so Glenn and Nicholas fall into a horde of zombies, which ultimately appears on Glenn's death. Understand that both the death of Nicolas, as Glenn's death were not explicitly shown in the episode.
Human shield theory (anatomy + lucky)
Shocked, Nicholas decides to commit suicide, Glenn and Nicholas fall into the zombie hord
e which would result in certain death, however, Nicholas falls over Glenn providing a temporary protection against zombies.
This is reinforced by the fact that the images show very similar guts to the abdominal viscera, especially the intestine, possibly discarding the Glenn hypothesis have been gutted in the upper chest (what the pictures suggest).
Hallucination theory (short, but plausible)
I'n this case the hallucination might have happened in Nicholas or Glenn's mind, but I will focus on Nicholas.
Nicolas is detached from reality and ultimately figure out how and which could lead to his death and Glenn then, this is partly because of Nicholas in previous episodes have shown the coward that would facilitate the kind thoughts and imaginations occur.
Another detail to consider is the weapon of both Glenn and Nicholas were out of bullets, forcing the Glenn and Nicholas opt for the knife after the end of the bullets, which obviously prevents suicide with a gun.
Hallucination cases have been witnessed in previous episodes by Rick and Tyreese.
The Savior
The end of the episode starred Rick and Daryl both possible saviors of Glenn, let me explain.
The end of episode Daryl get away from Abraham and Sasha to go toward Rick (possibly also near Glenn), só, if Daryl find Glenn this increases the possibility of Glenn salvation.
Also at the end of the episode Rick is surrounded by Wolves, and after having a hand-to-hand combat he uses an automatic rifle to kill the other targets that were out of the trailer, the irrational use of the rifle caused the noise that attract Walkers for close, which would divert the attention of Walkers surrounding Glenn, giving it a breach of salvation.