When Gemma and Tom are leaving in their silver VW, the car is shown with alloy wheels. During a close-up a moment later, the alloys have switched to plastic hubcaps, and then back to alloys.
When Gemma and Tom are trying to leave that strange neighborhood with the car, Gemma is looking at their both cellphones. None of it have phone network. But they could have use the GPS instead, to find out where they are, and find a possible way out - except that there is no reason to suppose that GPS would ever work, in an alien realm where space & time are distorted, and the ground itself can be bent & twisted.
No one bothered to teach Jesse Eisenberg how to use a shovel properly.
When the main characters are dancing in front of the car you can see a crew member hiding behind the car door.
Tom's hands should be blooded and very painful from constantly digging.