These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Fore Shadowing: In one of the alternate endings for Season 1, Eric falls off the roof of Alcatraz and survives; establishing that a fall from Alcatraz alone is not fatal. Later, in Season 8, it is revealed that Shawn also survived the fall from Alcatraz that he took in 5-8
Moral Event Horizon: Shawn Mallory's Sanity Slippage propels him across this when he doesn't just kill Hartnell—justifiable to save Willis's life—but also marks him as a thrall so he'll die in horror that he'll be a nothing in the afterlife at the end of Season 4.
Player Punch: Tasha King in 3-7, Phil Morris in 4-8, and Ken Greene in 8-6. You will want to return their killers to nothing afterwards.
The Scrappy: Óscar Santos gets way too much flak. Not because of his occasional overblown ego, but for obstructing a relationship between Mal and Natara.