Plot hole: The book says the demon has to devour 5 souls in order for the abomination to return, but it only got 4 since David saved Mia's.
Suggested correction: In the extended version, we see Mia's soul isn't actually saved.
"In the extended version" has no relevance. Bonus content holds no weight when leveling criticism at the theatrical cut of a film.
Suggested correction: Actually, more than five souls were claimed over the course of the film, whether or not you count Mia. Four people died in the cabin, plus the possessed girl in the beginning of the film, in addition to the girl's mother, who is mentioned to have been killed by her. You could also make an argument that the dog counted, technically. You also gotta remember, the book said the souls must be "consumed," and technically, it did possess Mia and she "died" while still possessed before being revived. So by the vague definition of "consumed," she could still possibly count. Either way, definitely more than five souls were claimed over the course of the film.
Brother and friend were also technically cleansed by fire.
Plot hole: When Chucky is decapitated, no blood comes out. He still has the scars from Bride/Seed of Chucky so that means he's still in the same doll's body. The longer he remains inside the doll the more human he becomes, so he should definitely bleed by this point in time.
Suggested correction: There's no telling exactly how his Voodoo works.
Plot hole: The room that the teens are kept in while being fattened up is locked up by a single, wooden, thin door with a conventional doorknob as the only lock. That door is way too flimsy to hold them. Two strong teenage boys with two girls there as well could have easily broken the door down with little effort and escaped.
Plot hole: When the mom spots the tornado behind them down the street, she brings the car to a screeching halt on the side of the road and orders the sisters to get out. They then take off on foot down a long driveway to get to a stranger's house. This is an illogical decision. If wanting to hurry to escape the tornado, why stop at the driveway and take off on foot? They would have reached the house much much quicker by driving down the driveway to the house. (00:14:55)
Plot hole: The same zombie who can smell through a vault that Gerry is not worth a bite, just minutes before couldn't smell the presence of three alive humans two meters apart.
Plot hole: The beginning of the film takes place in 1973 right after the original Texas Chainsaw film ends. Right after the house is burned, one of the townspeople takes a baby who survived the fire who is Heather. The film then takes place in 2012 but Heather seems 20 years old and should be 39.
Plot hole: When Gretel is going through the weed maze the first time to find one of Carlos' goons in the cage, Agnes' dog is gone. But just earlier, she told her dog to stay there right by the cage, and the dog did so, and did not leave the garden. Yet Gretel is there and the dog is not seen, nor does it show up or attack her, despite all the loud noise, leaving a trail of Skittles, and the whistling. It does not make any sense that the dog would have vanished and not attacked Gretel. The writing even missed out on a good action scene there.