This movie is full of destruction and contains destruction of places like Hawaii and Hong Kong and other major cities.
Multiple ships, both human and alien, are sunk, almost always accompanied by massive explosions and eardrum-rending noise. Alien shells embed themselves in hulls and then explode, ripping boats apart. We see scrap metal fly and wreckage sink, dragging dozens, perhaps hundreds of people into the depths. A sonic boom blows out windows and makes the faces of sailors shake like Jell-O molds. But perhaps the most fearsome weapon in the aliens' arsenal is the metallic shredder, the edges of which tear through metal (cutting through an entire ship, sinking it) and concrete (causing part of a freeway to collapse, sending several cars crashing into a gaping chasm).
Even when the alien ships crash, they're deadly. One hits a satellite on the way into the atmosphere, breaking apart as it descends. A chunk smashes into a Hong Kong skyscraper, sending the building tumbling. In news footage, we see wreckage and fleeting riots in the streets. We hear that 25,000 people have been killed.
While the body count is undeniably high, the movie rarely shows much blood beyond lacerated and bruised faces. We do see countless injured people strewn about ship decks or being taken to infirmaries.
The aliens engage in fist-fights with humans and one punch sends three alien teeth flying in slow motion. They destroy two police jeeps tearing them apart and leaving the corpses in the resulting wreckage. Alex falls hard on his back while breaking into a convenience store. He's Tasered twice by police officers while trying to escape and we see the resulting taser wounds on his back the next day with him complaining of the pain.
One scene is set in a veterans hospital with large numbers of amputees, with and without prosthetic limbs. They are all old injuries and no open wounds are shown.