* So many things about the Skitters - their appearance, the harness implants they put in the humans' spines...
** [[spoiler:The fact that the harnesses transform them]] does not help.
* The scene where the children are being harnessed.
* The [[HumanoidAbomination Overlords]].
* [[spoiler:Ben's progressive transformation.]]
* [[spoiler:Jamil's death]]. Remember those flesh-eating scarabs from ''[[Film.TheMummyTrilogy The Mummy]]''? Picture a Skitter version of them, make them bigger, and make them eat their victims ''from the inside-out''...
** The fact that ''several'' of these creatures crawl out of [[spoiler:Jamil's]] mouth didn't help either.
* [[spoiler:Anne's baby.]] Yes, this show managed to make [[spoiler:a baby]] severely eerie...
* [[spoiler:Hal getting Karen's bug removed.]] ''Not'' a pleasant scene to watch.
** The parasite being removed from Tom's eye in "Shall We Gather At The River." He's fully conscious and screaming the whole time.
* Anne has a dream in season four. [[TakeOurWordForIt It involves her pregnant belly and an Overlord]].