During the first explosion at the house, windows are breaking all over; in the next scene inside the house, there are no broken windows anywhere. Again at Grandpa's house, there is an explosion and broken windows, but inside the house where Nathan is, there are no broken windows.
At the end of the film, when the various ruined cities are shown, Paris is seen in shambles but is still recognizable. Later on, the closing orbital scene shows France and the entire Iberian peninsula to be completely underwater. Even if it wasn't, such close proximity to the big impact as shown would have wiped Paris completely clean with nothing left.
In the supermarket, when Nathan (Roger Dale Floyd) is picking out his favorite juice, he points to the orange juice and John (Gerard Butler) grabs it. After switching to a wider shot, the orange juice is back on the shelf and the berry punch juice next to it is missing.
When the first shock wave hits John Garrity, he is blown to the ground by a powerful gust of wind full of dust, dirt, leaves, twigs, and other small debris. As soon as it has passed, he immediately gets up and is perfectly clean, unruffled, and without a hair out of place. He should have been disheveled and covered in debris.
(At 1h 25min) When the family is packing up the truck to leave Dale's (Scott Glenn) house, Dale puts a car seat on top of the truck bed. In the next shot, it is gone.
The plane that flies the families from Osgoode, Canada to Thule Base, Greenland (about 2,200 miles) is a DHC-6 Twin Otter with a maximum range of only about 900 miles. Even if it did have the range, a Twin Otter would take about 11 hours to to cover the distance, not 6-8 hours John Garrity estimates. The "big one" would have hit Europe before the plane arrived.
Nathan (Roger Dale Floyd) says he has low blood sugar and his mother (Morena Baccarin) gives him extra insulin. This would lower the blood sugar even further. He actually needs to eat something.
In the film, there is often no delay between the visuals of an impact far away and the sound of it. In reality, the impacts would be silent, followed by a shock wave through the ground sometime later and the shock wave by air much later.
When Nathan (Roger Dale Floyd) appears unwell outside the airbase, Allison (Morena Baccarin) confirms that his insulin pump is running empty and then proceeds to give him candy. Were his insulin pump empty, his sugar would be running high; giving him candy would be dangerous.
At the first explosion, a blast that big, with that big of a shock wave, would certainly knock the electricity out.
When the soldiers "wand" the family with metal detectors, they would have discovered Nathan's insulin pump. Then they would have told the family "no chronic diseases" and the family would have stayed together at that point. However, the pump (nor their cellphones, keys, etc.) wasn't detected because the wands were only looking for very large metal objects, such as handguns, not smaller objects, which would have needed close "wanding" over the people's bodies and limbs, not a cursory wave over just the body.
(Around 39 min) Many soldiers are seen exiting the gate with one shouting there is a breach (people have gained access to the area). It is unclear why the soldiers would be exiting the gate rather than attempting to reinforce it and remove the trespassers. The soldiers are clearly being dispatched to the area of the breach, as seen by their arrival to confront the mob on the airfield.
In the end, Nathan (Roger Dale Floyd) finally arrives at the shelter with presumably only a week's worth of insulin (provided by the military nurse) and the original small quantity recovered from the car by the father. If the shelter wasn't accepting people with medical conditions, logic implies they would not have any insulin for diabetics. However, it is very likely that those making the rules would exclude themselves, and some in authority (e.g., former UK Prime Minister Theresa May) are diabetic, and others might be expected to develop the condition during the several months of "incarceration". It would be more of a plot hole if the boy had died for want of insulin.
The QR code that John Garrity uses to prove that he and his family have been selected for extraction contains nothing other than his name, "GARRITY, JOHN A", which anyone could create and use as proof. His actual identity is never verified at the control points.
The main characters at the shelter's entrance in Greenland at the end shouldn't be able to see the "big one" entering the atmosphere in such a low angle if it was supposed to impact Western Europe. Even if they somehow could see it, due to human miscalculation and it landed much closer to them, they would've been blinded by the sheer light from the atmospheric entry and burned alive by its heat even before it touched the ground.
At several occasions in the film, phone displays are on during phone calls. Actual phones have proximity sensors that turn off the screen to prevent unintended touchscreen interaction.
At the beginning of the film when John is at work, he looks at his phone's screen saver. As he locks the phone, it shows the time as 1:50. Moments later the time on his watch is 2:25.
After finally reaching Greenland, the plane makes a hard violent landing and comes to a stop by crashing into the base of a mountain. None of the passengers are wearing any type of restraints. Small children are shown only sitting on their parent's laps. Yet somehow, they all remain neatly in their seats. The overwhelming forward momentum of such an abrupt stop would have thrown the unsecured passengers forward resulting in many severe injuries and most likely deaths.
During the trip to Warner/Robbins AFB, the highways are not especially congested as would be expected for a catastrophic event such as this.
During the highway scene, there are a couple of moments where pieces of molten debris raining from the sky in the far background fall at noticeably smaller frame-rates, almost as if they were 'lagging'. This is most discernible when the helicopter crashes.
When the family leaves Dale (Scott Glenn) at the farm and gets his truck, a Wunderbaum hangs in the rearview mirror but is gone in later scenes.
When the pickup is driving through New York, there are highway markers for Georgia.
The waterfall that the characters can see when flying over Greenland is actually the Skogafoss waterfall, located in Iceland.
Thule Air Base (BGTL) is actually located in far northwestern Greenland, near the Arctic Circle, not southern Greenland. It is also situated right next to North Star Bay, where the base in the movie is located in a lush, mountainous valley some distance from the coast.
When John (Gerard Butler) gets in the truck to go to Lexington, he says it's "on the way" to Canada. But the driver is going toward Ottawa off I-95. Lexington is off I-75 and hundreds of miles to the west out of the way. Maybe a few hundred miles, more or less, isn't a huge detour considering the over-1,100 miles of the total trip.
Several TV and other announcers make reference to Eastern Standard Time. If this movie is set in the summer, it would be Eastern Daylight Time.
Colin (Andrew Bachelor) tells John (Gerard Butler) they are going to Osgoode, Ontario, where private planes are flying to Greenland. In actuality, there is no airport in Osgoode, at least none with paved runways. Osgoode is less than 20 miles from Ottawa International Airport.
When they reach the traffic jam and John starts reversing, Allison calls John, Gerard.