Revealing mistake: When they are in the hospital van, taking the senator to triage, and they receive fire from the helicopter, one announces that "Randall is dead" referring to the young man in the back of the van. It then cuts to his corpse - however, a split second before the scene changes away from his face, his eyes move towards the camera. (00:56:35)
Revealing mistake: During the scene near the end, at the climax of the film, when Ed is holding onto Janet for dear life outside her bedroom window, as Lorraine rushes over and pulls them back into the house, 'Janet' is a dummy.
Revealing mistake: As Joe is gesturing, the wrinkles of the gloves worn to make his hands bigger are noticeable.
Revealing mistake: When Austin goes to write the Roman numeral "XVII" on the chalkboard, the erased numerals from a previous take are still visible where he's about to write it. (00:41:36)
Revealing mistake: When Lockhart slices his cast open, his missing tooth is just cosmetically blackened. (01:47:00)
Revealing mistake: Right after the little girl sprays the monster with bug spray, you can see the costume of the monster, it's wearing a black cap. (01:19:00)
Revealing mistake: Just after Sang-hwa and the baseball team seal the doors, it cuts to a man in a checkered shirt clinging onto a set of chairs, getting attacked by a zombie. In the closer shot of the zombie biting onto the man's neck, for a brief moment, a blood pack can be seen just above the black T-shirt he is wearing under the checkered shirt. (00:45:43)
Revealing mistake: When Gabby and Fin are hanging off the building in Las Vegas, you can see that Gabby isn't holding on to anything in some close-up shots. (00:11:47)