Backed by the Pentagon: The USMC provided a number of troops to serve as extras, and lent a huge amount of aircraft such as various helicopters and even V-22 Ospreys. They also allowed the crew to film some parts of the movie in Camp Pendleton. Behind the scenes, the cast were trained at a boot camp run by military advisors to make sure they acted, fought, and spoke like Marines. Aaron Eckhart joked that they were very particular about the terminology they used, such as calling a helicopter a "helo" instead of a "chopper".
Fan Nickname: The aliens are never really named — there are lots of nicknames. Some call the aliens "BLAAs" for "Battle Los Angeles Aliens".
Life Imitates Art: Interestingly, the 2011 Tohoku earthquake and tsunami happened the day this was released in theaters, so as the movie about things coming out of the water and attacking Los Angeles was released, Los Angeles (and the rest of the Pacific Ocean) was under threat of a tsunami coming out of the water and "attacking".