[[caption-width-right:350:Suddenly I don't feel so guilty stepping on ants. [[note]]Fun fact: the JPG of this image was called ''[[BlackComedy Bad Picnic]].''[[/note]]]]

* The killer ants that ''eat people alive''. Oh yes, and they're coordinated enough to form a tower to reach you if you're out of reach.
** Know what's scarier? Though they don't go after humans, there are ''really'' insects like that in South America. This was NOT science fiction.
** That moment when the ants use their own bodies to build a tower and reach higher? Also real.
** When Dovchenko is dragged into the anthill, you can hear him yelling something. [[BilingualBonus It's Russian for "Help me!"]]
* Spalko's death from too much knowledge is pretty horrifying. Even more so in the adult novelization. As the alien beings leave this world, Spalko actually feels her skull painfully transform into quartz as the aliens flood her mental consciousness with all the knowledge in existence. It gets worse, and just before she dies Spalko gets a terrifying glimpse at the {{Eldritch Abomination}}s.
* A suburban neighborhood populated by [[UncannyValley eerily smiling plastic dummies]], complete with [[SoundtrackDissonance "Howdy Doody" playing on a TV set]]. The creepiness isn't reduced by the fact that [[spoiler:it's a nuclear bomb test site]].
* Irina Spalko's plan for the Crystal Skull, i.e. [[spoiler:using its power to brainwash large numbers of people into mindless followers of communism]] is downright terrifying, and the psychological nature of this attack is what makes it so bad.
* TheGreys have always been creepy but to have one looking super pissed like the resurrected alien was at Spalko at the end? Terrifying.