Other mistake: The time on Jin-hee's phone is 1:56PM when she gets a text from Yong-guk. But later on, when Yong-guk calls Jin-hee's phone and Yon-suk breaks it when attempting to get into the zombie-free car, the time is 3:31PM. Only a handful of minutes passed in between these scenes. There's no way over an hour and a half could have passed. (01:03:25 - 01:09:47)
Other mistake: When the truck driver gets his truck cleaned at the start, he starts to drive forwards to a worker at the quarantine checkpoint. The wide shot shows the truck driving towards the worker, but when the shot ends, the truck has not quite gone passed him. We are then shown a shot of the truck driver stopping the truck and rolling down the window. In the shot, the driver is shown looking directly to his left to be face to face with the quarantine worker, right as the shot begins. There's no way the driver could have been immediately looking at the worker at the start of the shot as the truck had yet to go past the driver at the end of the previous shot. (00:01:20)
Other mistake: When Jin-hee gets a text from Yong-guk saying that the people have been rescued and are heading back, the time is 1:56PM. This time is not possible given the events taken place prior. First, the train set off early in the morning, and every time a phone is shown after the outbreak starts, the time is always in the 7AM hour. For example, when Seok-woo is reading the texts from Kim, the time is 7:16AM and when he is on the phone to ask about the military being deployed in Daejeon, the time displayed is 7:20AM. The events of the movie after this point mostly play out in real time, with the only part being skimmed over was the remainder of the journey to Daejeon Station, so there is no way over six hours could have passed in between these two points. (01:03:25)
Other mistake: When the truck driver his the deer with his truck, he steps on the brakes and stops the truck instantly. Just after the truck is shown bumping up and down after hitting the deer, outside the window, we can see the driver travels a small distance until the truck stops, maybe three of four meters at most. When the man is getting out the truck, we can see the distance between the truck and deer is much further than what was shown between the time he hit the deer and when the truck stopped. (00:02:14)
Other mistake: When the truck goes through the checkpoint in the opening scene, it is sanistised and cleaned with a water spray. We can see that water is sprayed across the driver side window, and then the driver roles down the window to talk with a worker. Once he has left the checkpoint, he is shown driving down the road with the window roled up again, but the water that was sprayed on the window appears to resemble tiny droplets. The water would have been wiped away when the window was roled down, or at the very least would have been smeared across the window. No way would the water appear as droplets sprinkled over the window. (00:01:20 - 00:02:00)
