Zoe drives the van outside where it detonates and comes to a standstill against a car. But in the next shots the van is seen standing in the middle of the car park nowhere near any cars.
The guy who got run over by and got stuck under the front of the van when the van enters the canteen has disappeared at the end.
When Zoe and Lewis are chatting in the canteen a guy in a blue T-shirt sitting behind Zoe keeps disappearing and re-appearing between shots. This is evident in both close ups and the long shots.
A balloon full of hydrogen ignited in a classroom will not cause a minor explosion. It will cause hearing loss and serious damage to the room, and probably even wounds to those standing too close.
When Kip shoots at Zoe, he fire three rounds in succession from his double-barreled shotgun, but does not reload before the third shot.
The magazine of the MP 40 submachine gun holds 32 rounds. The bad guy equipped with that weapon fires a multitude of that number of rounds without ever reloading.
The barrel on the MP40 is at times bent downwards at an angle, revealing it to be a prop, in contrast with the live sub-machine gun that is shown firing.
The shotgun shells Zoe is seen loading not only do not have a crimp, or any visible shot, bit they don't even have primers. They are very clearly empty props.
The angle of the hole of the bullet in the window does not match the angle of the shot fired by the hero's father.
@ 1 hour 20 minutes when Zoe enters the canteen during the siege a shadow of a camera can be seen on the wall behind her in the bottom right corner of the screen.
When Tristan is talking near the van, right when he kicks the door: There is a crew member covering up a window to the rear left, then walks away.
Gunfire in a cafeteria would have been heard throughout the building.
At 1:35, a cop is supposedly arresting a character on the ground. He slips a zip tie over their wrists but makes no attempt to tighten it before moving away. The zip tie would consequently come off as easily as it went on.