In a timeline where Phi is killed and Sigma and Diana get stuck in the bunker, Diana turns to alcohol to deal with their situation and has to have a bottle forcefully taken away from her by Sigma.
Injectable drugs of various kinds are used throughout the game, both through the game's bracelets and external needles. None are recreational, however.
One escape room features a dead pig that has to be cut open. The same room also features a dead penguin, seahorse, and human fetus, although these are all in capsules that the player cannot and doesn't need to open.
Carlos makes a sudden and out-of-character pass at Akane before knocking Junpei across the room and forcibly getting on top of Akane on the couch. He doesn't get very far before Junpei stops it, and it's later revealed that he did this to whisper something in Akane's ear without Zero catching on. However, even with the lack of intent to actually follow through on the assault, Akane is clearly terrified of Carlos and the reveal doesn't come until much later.
The game's cover shows this scene: One character must be restrained to a chair for the sake of a puzzle. Depending on the player's choices, that character may live or die. After the puzzle, the character is released.
Not the traditional way, but one timeline gives the player a decision to push a button in the shower room to send hydrogen fluoride pouring down onto the other teams. This burns and melts their bodies until they are dead.
Sigma attempts to defuse a bomb and fails. Although he survives the explosion, he comes back to Diana and Phi with bloody stumps where his arms used to be and a piece of shrapnel in his eye.
One escape room ends with a small fire, which triggers a carbon dioxide fire extinguisher built into the ceiling. It continues to spout carbon dioxide as the characters attempt to escape and audibly struggle to breathe. Depending on the player's choices, either two or three of the characters in the room suffocate. There is no way to save all three.
Sigma attempts to defuse a bomb and fails. Although he survives the explosion, he comes back to Diana and Phi with bloody stumps where his arms used to be and a piece of shrapnel in his eye.
While Sean isn't technically a child, I'll say yes because for all intents and purposes he takes on the personality and appearance of one. In multiple timelines, he does die and often his body is shown. There's also a timeline where it's implied that a pair of newborn twins starve to death, although there's a game over before it shows any of that.
Multiple characters have backstories involving dead parents. In one ending, a pair of characters get stuck in the bunker and have children. The story ends with the characters running out of food, sending their kids' atomic data to the past (don't ask), and the game ends there with the implication that they died of starvation.
Zero, after his true identity is shown, is revealed to have the ability to control people's actions. In the early game, him using this ability takes on all the appearances of a posession.
Sean frequently has flashbacks to a hospital, although it is never shown in detail. There is also an escape room that takes place in an infirmary with various medical equipment, including a CT scanner.
Mira describes not understanding human emotion, including facial expressions. It's revealed that she's a serial killer called the Heart Ripper, a killer who extracts their victim's hearts. She states that she doesn't feel or understand emotions except for when she literally touches someone's heart. When this is revealed, Eric has died of other means and Mira bloodily extracts his heart. All of this is shown in detail.