A man fires a hi-tech gun in a street that causes a large explosion and knocks him backward.
A lot blood splatters when aliens get shot but all blood is green or blue.
A lot of the violence is implied rather than shown.
An alien dressed in a human suit is shown holding a man's head, which turns out to be fake.
An alien is shot, causing him to fall over and die.
An alien dressed in a human suit throws himself off of the roof of the building (this is not actually shown; all we hear is a splat then his body is shown lying on the ground surrounded by a crowd of people; there's no blood).
An alien disguised as a human falls off a building. However, we cut away as we hear its body hit the ground (it is implied he does this to avoid a worse fate at the hands of the alien he was working for).
A man's skin is changed into a alien.
A man is shot but it turns out he's an alien considering immediately and he's fine.
A bug extermination vacuum-type hose is used on a man.
A pregnant alien woman disguised as a human gives birth in her car, but nothing graphic or explicit is shown (it is meant for comical laughs, as she grabs J with her tentacle and starts waving and shaking him around).
The alien "bug" attacks two aliens in human robot bodies in a restaurant.
A man is pinned up against the ceiling by layers of the alien bug's slime.
little organisms are shown coming out of the bug's mouth.
The bug removes the human skin to reveal his true identity, this entire process may seem a bit gross or even disturbing to some people.
The bug swallows "K", and some of its inside is shown briefly.
The bug is shot twice, both times showing his guts and insides spewing everywhere, including on "K" and Smith's character.
There is a long scene in the morgue where a medical examiner is working on a dead alien.