Justine's age
In Pulse 2, it's established that Justine's age is 6 (her father says so in conversation with Marta when he's asking her not to drop so many F-bombs)
This movie is set 7 years after Pulse 2, meaning that Justine should now be 13, not 17. This seems like a fairly large screw-up in continuity.
There's always something to look at if you open your eyes.