Continuity mistake: When Sam is in his bedroom, after he finds the Cube sliver it falls and dramatically burns a hole through the floor into the kitchen. But Sam's bedroom is over the living room (there is nothing on the ground floor below Sam's elevated bathroom, and in the first movie Jazz hides in this open space), and the kitchen is actually located between the den and dining room, at the other end of the house. If they were to follow the actual floor plan of the house, the Cube sliver would have landed in the area of the piano in the living room, but where would the fun have been in that? (00:12:30)
Plot hole: During the later parts of this movie there is much talk about 'continental displacement' and this appears to be happening in the film. The Earth's crust is falling apart because of the heating of the inner core, and all the cities seems to be falling apart since the ground can no longer hold them. When our cast finds themselves surprised to be already over China when they figured to be over the ocean, it is explained that Asia has actually moved from where it was. If this phenomenon is taking place globally, how come the monks in China don't seem to have been disturbed at all? In fact the bell the monk rings as the ocean approaches hasn't even been shaken. The arks are built in between the mountains, but the mountains are apparently fine. Shouldn't they be falling like the rest of the crust?
Continuity mistake: In the scene where Parker is shown playing golf on the indoor golf course in RDA, the first time he hits the ball, there are two other balls lying on the course side by side. In the next shot, two are distant apart and in the shot after that, they are in their original position. (00:12:15)
Other mistake: When Marcus, Kyle and Star are at the petrol station, a flying HK and the giant Harvester robot are able to appear just outside without making any kind of sound. In every other scene of the Harvester and the HKs however, they both make an incredible amount of noise. (00:37:40)
Continuity mistake: When Grumpy jumps the chasm to chase Dr. Marshall, there's a large green bulbous plant that moves from the side Grumpy jumped from to the one he lands on. It wasn't there before.
Factual error: In the underwater scene when Rex blows up the ice pack, ice appears to be denser than water in this situation. The ice sinks when it's blown up, and even if there were pieces of metal on top of the ice, it shouldn't. Some pieces the size of a five-story building have no metal and still sink. (01:43:00)
Continuity mistake: After the car chase, the front plate of the taxi is hanging on one side. Moments later, while driving the cab and fighting the other "alien," the plate on the taxi is in a different position (semi-fixed). (00:46:00)
Factual error: Abby has trees surrounding her house yet there aren't any in Nome Alaska.
Continuity mistake: It's shown in many scenes that the robot Gallaxar sends isn't particularly quick moving when it walks. But when it's chasing Ginormica around the city, even though Ginormica is sprinting away, it can catch her far more quickly than its speed would allow. It doesn't suddenly speed up - in the shots when the camera focuses on the robot again, you can still see it moving slowly.
Factual error: In the beginning a calendar says 2019 April, you can see April 1 being Tuesday when actually April 1 2019 was a Monday. (00:01:10)
Continuity mistake: During the prison fight scene, Silk Spectre's stiletto boot heels are alternatively flat-soled from shot to shot, for the stunt woman's benefit.
Plot hole: Despite their awareness of the red matter and the power of the singularity, no one on the bridge had the common sense to suggest pulling back to a safe distance. Nero had already refused their assistance so there was no need to stay so close to the singularity. And when a black hole was created inside Vulcan, an officer mentioned they had to reach minimum safe distance, so they know what they need to do, but no-one does it. (01:00:30)
Revealing mistake: When the old couple who give Wolverine clothes are first driving towards their house, there is an aerial shot of them driving over a bridge. This is supposed to be set in Canada (drive on the right) but it was filmed in New Zealand (drive on the left). They are driving on the right but the arrow on the road is on the left side.
Continuity mistake: When 9 meets 3 and 4, they open his zipper. During this scene, several close-ups show 9 with the zipper closed and open again without anyone closing or opening it.
Factual error: When Sam speaks with his daughter on the long range phone there is virtually no delay between some questions and answers. It takes over two seconds for radio waves just to travel from the Moon to the Earth and back in a straight line. The interval between question and answer physically can't be shorter than that and realistically should be around 3 seconds or even more, accounting for additional signal relays and time needed for a person to form a statement. Same for the communication between Gerty and the Lunar employees when Sam 2 got out of his infirmary bed.
Continuity mistake: After the interview, in a 3/4 back shot, we see Castle putting a lollipop in his mouth. The shot instantly changes to him kissing the host's hand - no lollipop in sight anywhere. It then changes back to the original shot with the lollipop in his mouth.
Continuity mistake: Near the end of the movie, when Christopher is pulled from the armored car and questioned about his plan, his arms are tied behind his back. A little later, when he is kneeling and the order is given to kill him, his arms are still tied. When Dinkus returns, Christopher is still on his knees, even after a soldier to his left explodes. A moment later, Dinkus arrives in front of him and Christopher is still on his knees, but now his arms are free.
Continuity mistake: Claire sits on a blanket and empties a bag of stuff on it. Then it seems empty when she takes it from the ground to hand it over to Henry. The stuff would have sounded and the blanket is to light when she takes it from the ground to hand it over to Henry.
Continuity mistake: While Sam is talking to Trudy in the bank about the burned church, the name tag on the door in the background when the camera is focused on Trudy is there, then it isn't, then it reappears again throughout the scene. (00:35:30 - 00:36:00)
Visible crew/equipment: In one shot at the end, when all the surrogates fall to the ground, you can see a few crew members (one with a white megaphone) standing in the street in the upper left corner. (01:19:55)