This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Red Planet
The scene with the two astronauts are standing on the planet, in their space suits, slowly asphyxiating in their suits. And one of them takes his helmet off! Asphyxiation is NOT a fun image to have in your head. And yet, they survived, because Mars had already been terraformed? When did that happen?
The terraforming was something from an earlier mission they believe had failed. Turns out it was actually wildly successful thanks to an unknown Martian species of insect which just happen to devour Tom Sizemore through his suit later in the film that consumed the seeded algae and excreted oxygen in greater amounts. There are worse parts to the rest of the film, however:
Benjamin Brattwas killed earlier in a scuffle when he was shoved off an enormous cliff, without either person in the scuffle realizing they could've just taken off their helmets and lived.
Carrie-Anne Mossis nearly consumed by a fire in zero-gravity back aboard the main spaceship, then has to deal with depleted oxygen levels.
Terence Stampis mortally injured on the semi-botched landing on Mars (the craft basically an inflated Bucky-Ball), when a single side is punctured and his harness malfunctions. Paranoia Fuel for roller-coaster enthusiasts.
And finally Val Kilmergets to go through nearly all of these events, ON TOP of which is nearly freezing to death every night and constantly being stalked by the Killer Robot, and then, just when he might get off-planet by using an older Mars probe, he could screw everything up by not understanding Russian in a Wire Dilemma scenario.
The entire film is basically a "marooned on an island" survivor thriller, set on Mars. The robot, AMEE, is basically like a dangerous, man-eating tiger or something. Except, of course, it's man-made.