Factual error: When Ray leaves his wife Gina and his car is hit by the truck he should still be in England, but when he is being chased through the streets he is in South Africa, the cops in the car are not in English police uniforms or vehicle, police livery is incorrect, and all vehicles have South Africa plates, not English number plates.
Factual error: The old percussion double barrel shotgun is firing modern shotgun shells, which would never work or fit in that gun, and furthermore are also made of plastic, wrong for the era.
Continuity mistake: At the beginning Ava shoots the man's phone out of his hand through the car window. When the car drives away all the windows are intact.
Continuity mistake: Angelica has flowers on her dress. During the wedding, they disappear and reappear between shots.
Continuity mistake: When Kat and the protagonist have dinner, his hands swap between crossed or not depending on the shot. (00:28:32)
Deliberate mistake: When the kids are about to jump start the trap Phoebe hides behind the school bus door. Half a second later, when the trap opens, she's nowhere to be seen, not even jumping or stepping inside the bus. Then half a second later she has managed to get inside, turn around and protect her head while the bus windows burst. It all happens in real time for their hairs are still fluttering. It sure paces up the scene, but it's really awkward.
Plot hole: There is no reason at all why, being targeted by a few arrows by unseen enemies - a fire suppressed already by the salvo of their own archers - the Rourans would turn around their heavy siege equipment, away from the bulk of the enemy forces, and fire it, hurling a single heavy stone to the middle of nowhere when they have the whole rest of the army who could storm the rock the supposed enemy commandos hide behind, or the archers who could keep shooting - again, they proved to be completely successful. It also makes no sense that the all-powerful witch who made the warriors flee managed to do any of this, 'sneaking' by horse in the middle of the steppe.
Suggested correction: Mulan used the helmets of the fallen warriors to make it appear that a large force has flanked Rourans. Rourans didn't expect this new "force" and knew nothing about it. They didn't know its size. And while their original target seemed harmless, this new "force" was killing Rourans. Fear and death were the reasons. What you see in this scene is an enactment of one of Sun Tzu's famous quotes: "All warfare is based on deception. [...] Attack him where he is unprepared, appear where you are not expected."
What we see in the scene is laughable, and not because of the idea, which surely is based on the profound strategic motto you mentioned and we find in many folkloric tales in other cultures as well; what we actually see in the movie, is that she grabbed a couple helmets lining them up on a rock, and she shot a few arrows. Then she stops shooting, and we see helmets knocked down in their full view. The movie truly surpassed itself in showing it in the most phony way; had they shown her shooting from behind the rock responding to their fire, or the helmets not falling, or them just shooting at mist, terrified, it would have maybe worked. It's an enormous overreaction. That and, under no circumstance trebuchets are used that way anyway. And she did all this setup unseen, again.
In response to death, nothing is an enormous overreaction. Something or someone was killing them. They wanted to kill it, and they didn't have time for Facebook's famous brand of pseudo-myth-busting. What if they knew it was one girl shooting at them? They'd still have done the same. Being killed is a very personal matter.
Factual error: The "hard suits" the divers wear have soft, relatively normal gloves and soft joints. More akin to a football uniform with armor over spandex. They are at the bottom of the Mariana Trench, at 36,0000 feet below sea level. The pressure is over 7,000 psi. Without a hard suit, they would instantly be crushed.
Factual error: The Corvette owned by Bentwood is not a Z06 as shown in the movie. It is a 2014 C7 Stingray and can be identified by the Stingray logo on the side of the car.
Continuity mistake: While initially walking on the train, we can see that the bottom of Regan's feet are filthy dirty, almost black on the bottom. She takes a few steps off-screen, and we now see her feet are cleaner. (00:40:00 - 04:01:00)
Continuity mistake: In the intro, the woman shimmies off her shirt, which pools on the bathroom floor. She finds the obligatory corpse, screams, and gone is the shirt from the floor. (00:02:00)
Factual error: Smaller pieces of the comet start raining down in a highway setting. While small fragments of a comet can come down, they'd all be traveling at anywhere between 20 miles per second as the comet is an extra-solar comet. Those small pieces wouldn't make such piddling explosions, they'd be creating concussion waves that would rupture your organs and send vehicles flying. The heat even from those small rocks would ignite all foliage within 50-100 yards. (01:31:00 - 01:34:00)
Factual error: SPOILERS! While the ending of Al being arrested for murder at his own wedding is dramatic and cathartic, it wouldn't have happened that way. There's no way that the cops would have known to search the wooded area near the cabin; they would have needed to find physical evidence linking the cabin to Al; they would have needed to establish that Al had no alibi for the time in question; etc. None of that would have happened that quickly or that quietly.
Continuity mistake: When the girls are standing on the beach with the flares to guide in the German aircraft they are in two rows just a few metres apart. The view from the aircraft shows them much further apart, wide enough for the aircraft to land between them.
Factual error: The USMC Embassy Guard is an enlisted Marine Sgt. He is wearing a Commissioned USMC Officer's cover (hat) that has gold braid and gold oak leaf motifs on the visor. (01:20:15)
Other mistake: The Volvo the woman is driving has a front Oregon license plate numbered 643 ODS, but her rear license plate is 902 CSM. (00:02:55 - 00:03:45)
Other mistake: Vaughn was sleeping in the back seat of the van with his head leaning on Gina's shoulder. When the collision occurred, his body somehow straightened up and went head first between the front bucket seats, through the front windshield, and he was ejected/killed. Based on his sleeping position in the van, he should have rolled forward and been kept in the back seat by hitting the front seats. A sleeping person is also less likely to be injured/killed because the body doesn't stiffen preparing for impact. If the accident actually happened as portrayed in the movie, Vaughn's body should have had visible cuts and be covered in blood, not just have a small amount of blood coming out of the side of his mouth. (00:07:53)
Other mistake: The email that starts it all for Sid Straw, the announcement from the University of Pennsylvania that he has been chosen to serve on the reunion planning committee, starts off with a nonsensical sentence that no one from U Penn would have ever typed. It's obviously the product of a studio runner whose work no one bothered to proofread. (00:01:15)
Factual error: The Blackledges' car has a license plate that starts with 34. Montana uses the first two numbers on their plates to identify the county that the driver lives in. 34 is the number for Sheridan County which is in northeastern Montana where there are no mountains in sight, but the Blackledge ranch is set near the foothills of a mountain range as you would see in western Montana.
Factual error: While on the fishing boat, the flag flown has 50 stars, while the movie is set in 1941. The US didn't have 50 states, and thus that flag, until 1959. (00:30:08)