The dog seen in certain levels, mostly in the second act, remains completely unharmed, and may be seen napping. Other dogs potentially seen may be in distress, but remain alive.
An end credit level, in fact: Helping Hands. As of the act 5 update, this will trigger automatically after quite a bit of dialogue once you complete 5-X for the first time. It's coupled with a very emotional song...and one that's in 5/4, so it's a bit tricky.
Possibly. Dr. Ian cares for his mother off-screen and is late to work after she "had another episode", but as of the current build it's unclear what condition she has.
One of the patients has suffered from chronic insomnia for seven years--he's even known as the Insomniac. The rhythm treatment seems to give him energy, but it doesn't seem to be perfect.
Richard Hugh, the politician, has a 'devil' tail. It's not clear whether this is meant to be metaphorical or physical, but he's the closest thing we have to an overarching antagonist. Religious details are not gotten into, though 'hell' is used as a swear word.
In the level 3-X, one of the characters has a small breakdown during the song. It is nothing scary, they simply fall to their knees in the dramatic fashion that occurs in media. They are alright afterwards.
Cole Brew has a tendency to give the doctors the slip--first as part of 2-X (to Ian's chagrin), and then over the course of act 4 (which takes place on a train, and contrasts with Hailey who gets permission). He returns both times, however.
It's very mild, but if it matters to you, there are a few instances of 'hell', two usages of 'bloody' in the UK sense, and one 'damn', as well as a 'god' or two. There are no obscene gestures.
None of the child characters have their parents shown or mentioned, but they don't seem to be abandoned. Their parents are probably with them in the hospital, just not important to the plot.
Two characters are shown to be addicted to caffeine and nicotine, with the health complications and reasons for their relapses discussed throughout the game.
When you miss an input in a level where there is an animal, it may show one sprite of it looking sad or unwell. It is only temporary and not graphic or sad in any sense.
One particularly unwell patient does the whole "possessed person head turning 360 degrees with no regard for their neck" thing. Their sprite returns to normal after their stage is cleared.
If you get a Game Over on 1-X or 1-XN, the patient (whose head has been spinning this entire time) will have his head fall to his feet. It isn't gory, and his body seems more fussed than anything about it, but it's still off his neck.
It's worth noting that there's another particularly lousy injury in act 5: that of a torn rotator cuff. It's played realistically, and not as something the rhythm defib alone can solve.
Mr. Stevenson is said to have fallen down the stairs and broken his leg. The very next day, his wife, Mrs. Stevenson, slipped and fell in the exact same place. This is why both parties are in the hospital.
Nobody is shown to die in-game yet, but the lyrics of Helping Hands mention "the ones you couldn't save...the ones you could've saved". The general implications given the medical nature of the game are hard to miss, but the details are yet to be seen as of the act 5 update.
In 2-2, Supraventricular Tachycardia, patient Cole Brew presumably overdoses on caffeine, which he has been addicted to for a while. While this is non-fatal, it gives him a very intense SVT attack that you have to treat, and it's treated very seriously by the doctor attending to him.
In levels 1-X and 1-XN, a character is seemingly possessed by a virus. Nothing very graphic is shown since it is a pixel sprite, but it does do the possessed 360 head spinning motion.
To answer another comment - no surgical stuff. Lots of medically-accurate talk of injuries, heart diseases, diagnoses, and treatment plans. (As well as obviously fake and ridiculous illnesses described in the same straightfaced manner.)
No character graphically self harms, though two characters do have harmful addictions that they feed into. The game explores the health complications from these, and healing and recovery.
Many of the levels use a shaky / fast moving window as a visual distraction. This can be both the camera shaking and moving while in full-screen, or the window minimizing itself and rapidly moving around your screen.
Many of the levels contain rapidly flashing lights and colours. Some levels also contain visual glitches which may contain flashing lights and imagery. One of the cues, specifically for the SVT beats, shows flashing inverted beams. These cues vary in speed and can sometimes be fast.
Some levels such as 1-X, 2-X, and 1-XN feature minor audio glitches. The noises are not any louder than the other audio volume, but they can be sudden.
Dr. Edega sneaks up on the other doctors after 1-2, is seen watching the Muses in MD-3, walks in without announcement in the tutorial for 3-1 and after 5-2, and watches Lucky from the window in his room during the early part of 5-X. And if you trigger certain achievements...it seems he's watching you, too. On a lighter note, 1-2 has Hailey watching Logan be treated from a distant wing before running over, and 1-2N has him do the same to her.
Yes and no; the "intern" is explicitly stated to be the real-life player working remotely. A fictional virus affects the game screen in certain boss stages, faking game crashes, moving the window around in time to the music, or posting distracting notifications.
In the bonus level "Blackest Luxury Car," some characters are hit by a car if the input is missed. If the input isn't missed, they kick the car away. The characters are only shown hurt for a small moment before they continue running like normal.