Character mistake: When Hopper is being chased by the alien and he goes on deck, Rihanna goes into the control room and aims the cannon at the alien's head. Just before she fires she says "Mahalo" which is thanks in Hawaiian. It would have been better to say "Aloha", which is Hawaiian for hello and goodbye, just before she fires the cannon.
Other mistake: When Alex Hopper is being tasered and arrested for robbing the convenience store, you can see his shirt is almost clean on his back. But he fell on the bottles and sodas rack in the store, the shirt should have stains.
Factual error: After getting his silver star, Hopper is spoken to by a special warfare commander who has the Navy and Marine Corps medal. But the colors are reversed. The blue should be on your left, and the red should be on your right as you stand face to face in front of the wearer.
Continuity mistake: In the scene on the mountain where the Hawaii police ask Mick and Sam to leave the mountain. Mick and Sam ask why and they are told during the conversation that the aliens have blocked all cell phones, radio and internet but in the next scene with the police they use a radio to communicate with each other.
Other mistake: The shot of the fleet outside of the barrier is reversed. The Aircraft carriers landing deck is slanted right instead of left.
Factual error: There is a shot depicting the crew physically carrying a large shell from the rear turret of the Missouri to one of the forward turrets. That shell is supposed to be a 16" High Explosive shell which is also the lightest shell fired by the main battery. Those shells were roughly 5 feet in length and weighed 1,900 pounds and yet we see one being shoulder-carried by 6 men. They are also not utilizing the equipment designed for the purpose of moving these shells.
Continuity mistake: When Hopper climbs to the roof of the convenience store, the time displayed in the upper left corner of the screen (presumably a video surveillance camera) goes from 12:11.57 to 12:12.12, then back to 12:11.36.
Continuity mistake: At the scene when Hopper is playing soccer he receives a kick to his face, however the blood on his face changes between shots.
Factual error: During the ITV News "UFO Landing Confirmed" breaking news scene, the lower caption shows the text "Amateur footage confirms rumors". ITV News is a British news network and would spell 'rumors' as 'rumours'.
Continuity mistake: The USS Sampson has no Close In-Weapons System at the bow when the movie starts, but uses one to counter enemy fire later.
Factual error: When the alien ship crashes into Hong Kong's Bank of China building, flaming debris can be seen flying past the statue of the Big Buddha, which was also established in an earlier shot as being located just behind the financial area of the city, Central. In reality, the Big Buddha is nowhere NEAR Central, out of view of the Peak, and not even located on Hong Kong island - but on Lantau island, to the west. The Big Buddha is also not included in the Hong Kong city skyline.
Other mistake: Alex Hopper's brother receives posthumously a Navy Cross (2nd highest award) for attacking the aliens, but Alex Hopper only receives a Silver Star (3rd highest award) for saving the world?
Factual error: The first time the film displays the name USS John Paul Jones during the RIMPAC exercise it is shown as a destroyer with the hull number 65 (DDG-65 is USS Benfold) instead of 53.
Factual error: By the time the survivors of the JPJ arrive on board the USS Missouri, there are less than 3 hours before the satellite is in position. When lighting off cold boilers, it takes longer than that to get steam up, yet within minutes the bridge is informed that they have steam in all 8 boilers. If it was that easy, all the battleships at Pearl Harbor on December 7th 1941 could have gotten underway immediately.
Factual error: Loading the projectiles and powder in the 16 inch rifles is done using a ram. The projectiles seem to just glide in on their own.