In the flashbacks, a dog is killed offscreen by the mirror. No blood or anything, but you hear him whining so it's distressing.
In the present, the main character attempts to prove the mirror is evil by putting a dog next to it for it to “consume.†He's in a cage that is covered by a sheet. Someone frees the dog and he runs out of the house, presumably ok. This was in my opinion a poor choice by the filmmakers, because I was no longer invested in the main character after that. You don't come back from trying to kill a dog.
The Parents are implied to have been greatly influenced by the mirror. It's up to debate whether the parents were responsible for their own actions but the abuse comes from both parents and included physical, verbal, psychological and neglect.
At one point the mother heard a derogatory comment from the father and it's not confirmed whether the father said it and immediately denied it or if the mirror put that thought in her head.
It's not shown onscreen, but one character is described as having burned to death in a fireplace.
There is also another character whose face is covered in electrical burns though we don't see the moment that she experienced those burns.
A previous victim of the mirror pulled out her own teeth and placed them in a bag. An old photograph of the teeth is shown.
Another victim eats shards of a bowl which damages her teeth. She is shown eating the bowl but the shot is obscured slightly. The teeth are not seen but blood oozes from her mouth. Later in the film you can see her teeth in her mouth.
The two parents of the film's protagonists are victims of the mirror shown in the film. Through flashbacks we see how the mirror gradually possessed them. The mother is shot by the father several times, and eventually the father forces one of the protagonists to shoot him as well. These events are brought about by the mirror and it's effects, and the children are visibly distraught by the change in their parents behavior and their eventual deaths.
This is a weird one actually, the Sister never really kidnapped the Brother persay but she went through a lot of effort and persuading to keep the brother at their old house even though he wanted to leave.
This is a yes, while some may not find that as apart of body dysmorphia it actually is. The mom has phobias and worries surrounding her C-section scar and the mirror uses that against her.
No, but there is a scene at the beginning of the movie where a character speaks directly into a camera for several minutes, which may be triggering for some people.
In the present, the main character attempts to prove the mirror is evil by putting a dog next to it for it to “consume.†He's in a cage that is covered by a sheet. Someone frees the dog and he runs out of the house, presumably ok. This was in my opinion a poor choice by the filmmakers, because I was no longer invested in the main character after that. You don't come back from trying to kill a dog.