Other mistake: After realising they can track the mother box, Batman says they have to go back to his base to use one of his satellites to track it, and they all do so. Which completely ignores the fact that Cyborg could easily access the satellite feed directly using his abilities and display it to the others on any nearby screen in Star Labs.
Factual error: Let's go by the movie geography; our planet is a big matrioska. By diagrams shown, this Hollow Earth would be by the Earth's core, thousands of miles deep. They enter from a portal in Antarctica. And yet, Godzilla later in the movie burns a random hole in the ground in HK deep enough to reach it, roars through it and Kong hears it, and the ape easily climbs it to poke back to the surface. Even admitting you can do the magic "1,000 miles in 2 seconds" warp anywhere, the scale is ludicrous.
Factual error: In the nighttime hostage rescue scene, the rescue helicopter has its right and green navigation lights on, which are designed to show other aircraft where it is and which direction it is heading. This of course would not be the case while staging a clandestine operation in hostile territory.
Factual error: Lt. Harp is told by Capt. Leo that the Lieutenant has 56,000h of UAV flying time, That is ridiculous. Even seasoned pilots of the Military Airlift Command do not have that many hours. Drone pilots can fly up to 1,800 hours a year, and Harp hasn't been flying drones for 31 years straight.
Continuity mistake: In the desert digging, the Nova's trunk is open, then shut. (01:42:00 - 01:45:00)
Other mistake: The issued sidearm for the Spanish National Police is the H&K USP 9mm Compact, which has a capacity of 13+1 bullets, and the Civil Guards' is the Beretta 92fs/M9, which is a 9mm and has a magazine capacity of 15+1 bullets. As of 2020 the Beretta is being phased out for the H&K USP C. The police officer fires a total of 5 bullets from his Beretta then the slide locks back because its dry. He has no magazines for reloads either. I highly doubt the Spanish police issues 5 bullets to their officers. (00:33:00 - 00:35:30)
Revealing mistake: When "Snowball" is sleeping on Lena's bed, it is obviously a "stuffed double" (stand-in). Snowball is usually partially hidden behind the dog (so breathing doesn't need to be shown/mimicked). The failure of Snowball to make even a slight movement is a giveaway (e.g, no ear movement when Lena starts talking), but even the stuffed lion, in itself, is not a very good replica - it simply looks fake. (00:33:44 - 00:48:20)
Continuity mistake: The blue car gets pushed through multiple cars and is damaged. Shortly after in the same scene, the car magically appears undamaged.
Continuity mistake: After talking with Bullock on the roof, Batman is in his vehicle and talking to Hugo. On the screen, Hugo lifts up a glass to his mouth to take a drink, but when the camera cuts to a close up of the screen, suddenly his arm is lower, and he is once again lifting the glass to his face. (00:05:37)