The phone call where we hear a young girl afraid and confused about what's happening, and then jumps out the window because there was a tree near it — all as her mother tries to communicate with her and tell her to close her window. Everything else can be accepted as regular horror movie gore, but damn it, that is unsettling.
The old woman walking around the outside of the house and smashing her head against it, finally crashing in through the window. Gahhh.
The concept alone is very disturbing: Imagine you are walking down a street in a busy city, and it's just an ordinary day. Imagine everyone around you, including yourself, just stops in their tracks, and then for no reason, they just commit suicide in anyway they can. You don't know why, you don't know how, and if you get infected, there is nothing you can do to stop yourself from killing yourself.
Also the fact that it just one day came out of nowhere...and that it can start up again at any time without warning.
After splitting into two groups, Elliot's group watches as the larger group is affected, and gets to hear them commit suicide one by one with the soldier's sidearm. Even the hippie couple that had helped them out earlier.
Alma just went out for desserts with Joey, now he can't stop calling her. He'd probably have started stalking her.
The fate of Julian's group in the jeep: The driver stops in the middle of the street, then accelerates and slams into a tree. The driver and the front passenger are thrown through the dash. Only Julian survives, walking away from the jeep ...and right into the middle of the street, where he sits down, picks up a shard of broken glass from the wreck, and cuts his wrists.
The infected man laying on a grassy knoll shredded and diced by the lawnmower.
The two young boys getting shotgunned by a crazed homeowner who refuses to shelter anyone in fear of the toxin.
The guy deliberately getting himself mauled by lions at the zoo.
