As other user states, several cats seen dead. However more than stated as you see them buried as well, and again at the end of the film as a flashback. Skip from 53-56 and then just after 59 mins. Then skip at 1:30:20 to 1:30:40 (20 seconds)
A common theme and plot-centric device of the movie is a fly infestation in the house, and the antagonist sometimes possesses people by having flies crawl into their ears.
The mother commits suicide by hanging.
It should be noted that this occurs after the son dies, so he is in no anguish from this. The same cannot be said for the father.
A little after an hour and 10 minutes into the movie, one of the characters is holding a flashlight that flickers on and off a lot. Whole scene is flashing for about a minute
At one point, the father threatens guests in his home with a gun, but is convinced to put it down. Later, an old man shoots something to cause it to light on fire. At the end of the movie, the father shoots himself with a gun.