Factual error: She fires the entire magazine of a Glock into the alligator's mouth. When it is empty, rather than the slide locking back and the trigger freezing, there is an audible click every time she pulls the trigger. This could not happen.
Other mistake: Aerial views of Yonder gave the impression that a basic grid pattern was used - parallel horizontal and parallel vertical lines that form right angles; yards were of equal area, either a square or rectangular lot. [However, some of the views from the couple's car as they were trying to find the exit showed some slightly curved roads that didn't fit the grid.] Following the sun as a way out, the couple was jumping over fence after fence - but they could've simply walked along perpendicular roads.
Suggested correction: But they tried getting out using the road by car, and they felt that the roads were causing them to go into a loop. So instead they take a route they know for sure is straight. Btw, Yonder isn't real so the way the roads bend and how the grids are made up is purely an optical illusion.
Walking (not driving) along the perpendicular fences would be the same difference only easier and less exerting. If/when they encountered a fence that looked different, that's when they could jump over it to see if it made a difference. How could they "know for sure" that the fences they were jumping over took them in a straight line? Also, they realised the clouds weren't real, so following something in the sky (the sun) was not necessarily a good idea. [This will be my only response here.].
Continuity mistake: After being buried alive, Wake returns to attack Howard with a pick. There isn't a speck of dirt on him.
Continuity mistake: The inspector is showing the singer the gruesome images of her friend. As he says "It's how we identified the remains", she raises her right hand, but in the next shot it's with the left hand that she's touching her lips. (00:04:45)
Continuity mistake: There wasn't much blood noticeable on the axe after it was used to chop off the mermaid's tail, but a little later when the man was carrying it over his shoulder, it was heavily covered in blood and dripping. (00:14:17)
Plot hole: Dr. Seager told Beth that "It [Z] was all in her head" and only she could stop it. How, then, did her son Josh have the same "imaginary friend Z"? Moreover, if Beth had Z as a friend when she was eight years old, why didn't she remember him or have her memory jogged when Josh first told her about his friend Z? Also, if Beth told Z that they would be together forever (get married and have a lot of kids), why would Z need to go through Josh to get to her?
Revealing mistake: It was pouring when Adam, Hannah, and Megan got out of their SUV to talk to the Man and try to get help with the flat tire. As they stood there, no "rain" was hitting them and it became obvious that their partially wet-looking clothes were "pre-wet" - they returned to the SUV with the same amount of "wetness." Also, the rain was coming down in straight streams, all parallel. (The water flow appeared to be slightly angled to make the artificial "rain" look more natural).
Revealing mistake: When Gregory throws Tree through the window during the final fight, as Tree lands, you can see the outline of a stunt-pad on her thigh beneath her pants. You can also tell it's a stunt-woman, as her body is slightly stockier than Tree normally is.
Continuity mistake: The location and intensity of Lavinia's purple hair highlights vary throughout the movie. For example, the purple highlights on the right side were far more pronounced (two wide, distinct, vivid lines) when she got home compared to when she first met Ward. Lavinia rode her horse Comet home, so her hair would have been wind-blown and the highlights would not have been likely to be neatly straight down, especially since she has long curly hair. (00:05:10 - 00:07:13)
Other mistake: Richard's remote "vacation" cabin in the mountains has a mailbox near the house at the top of the long driveway and the red flag is up for outgoing mail to be picked up by the USPS - but it is highly unlikely (almost impossible) that a mail truck would go there. Mail delivery trucks do not have to go to largely inaccessible locations or up long driveways to a mailbox where the truck would have to turn around or back down the driveway. (00:34:16)
Continuity mistake: After Sara's mother sits at the table, the left side of Sara's hair suddenly has two clumps of strands running down her cheek and flipped in front of her chin. Sara's hair changes a few times with different camera angles. (00:44:52)
Continuity mistake: The girl and guy are in a hotel room and she kisses him good bye. You see her go out of the door and the door handle is on the left side and no chain hanging. Then when you see the door a few seconds later the door handle is on the right and the chain is latched.
Other mistake: Jethro said to Brian, "Shall I tell you how I know you're lying? Because when you said that, you looked up to your left." However, Brian looked to his right and Jethro even pointed to Brian's right when he was telling Brian that he looked to his left. (00:56:00)
Other mistake: The flight attendant pulled out a wheeled serving cart as she was talking to the other flight attendant. While shown from the chest up, it was obvious the flight attendant was moving her arms for a little while and it sounded like she was placing a few glasses on the cart then stopped, but the top of the cart was filled with glasses when the cart came back into view. Also, it was not apparent from where the flight attendant had reached to get the glasses. (00:11:25 - 00:12:12)
Factual error: The Sheriff of the small town is wearing Sergeant stripes on her shoulder sleeves. If she was a Sheriff then no chevrons should be on her sleeves.
Continuity mistake: When Charlie throws Scott over the balcony, he crashes into the chandelier and it partially tears away from the ceiling. Sparks ensue, but the light remains fully functional. The camera switches to Scott on the floor then back to Charlie where the chandelier can be seen worth all but one light out. There is no visible difference in the room lighting. Later, when Charlie is chasing Scott and Annie with the shotgun, Charlie screams "Lights out!" and shoots a fully functional chandelier.
Character mistake: Reina asked Cory if they could "do that thing" because it was helpful for her medical school training. Reina then put a raw slab of steak/meat across his forehead and made slits in the meat as well as jabbed at it. A medical student studying to become a brain surgeon should know about and practice the safe handling of raw meat. (00:23:10)