During the zombie attack scene on the hospital stairway, a zombie has part of his chest sliced off by an ax. In the next shot, that part of his chest is undamaged.
When ants are shown as proof of the machine's work, they are standing at a grass field, but the footage of ants shows little pieces of white stone as a surface.
When police is rushing to the door right after the scene where operator gets killed, one police car passes the sign for the hospital and then it is obvious that cut was made before the other one passes.
If you look at the lettering on the door while the police and George are at the Old Owl, you can see that owl is mistakenly spelled "Olw".
When zombie of a tramp puts blood on the first corpse, it can be seen moving before he even touches it.
The switchboard operator anticipates clutching her neck, though she is looking forward, and unable to see the zombie reaching around from behind for her throat.