Goofs

While in the "elevator" with Marty, Dana's bloodstains on the right side of her face completely disappear between shots.

When the kids are swimming in the lake, a green towel appears and disappears on Marty's shoulders while he's standing on the dock.

When Curt jumps into the force field the point of impact is impossibly high.

When Dana first enters the cabin she leaves the door open, the film cuts to Marty standing outside where we see the door close. When the scene cuts back to Dana the others are walking in through an open door.

When the Rambler is at the gas pump, the football in Curt's hand disappears.

It is explained by the show runners that nudity is a good thing because they aren't the only ones watching. However, it is later revealed that the only other ones watching are the Ancient Gods, and it doesn't make sense for them to gain satisfaction from human nudity.

One-way mirrors only work when the room on one side is very brightly illuminated and the room on the other is very dimly lit. In the cabin it looks like both rooms are equally dimly lit.

When Dana is saving Holden by stabbing a zombie coming through a ceiling trapdoor in the chest repeatedly, you can clearly see she is holding a retractable stage property kitchen knife as she backs away.

The RV has a traditional rearview mirror and side mirrors. The side mirrors make sense for an oversized vehicle, but the rearview wouldn't help the driver, as all it would show the driver is the interior of the RV.

When Marty pulls up in his car, the drivers side window changes from open to closed from shot to shot.

Negra Modelo beer does not have a screw top closure. Sitterson can be seen drinking from the bottle, which would clearly require an opener.

It doesn't make much sense that activating System Purge would release all the monsters into the facility, nor why it would be so easy to do with the flipping of a switch and push of a button. It would make far more sense that a System Purge would destroy all the monsters in the event of a security breach. It also makes no sense why any of the cells would be able to open into the lobby in the first place.

Blood trickles down into the carvings whenever (the showrunners believe) someone dies, but the Ancient Gods know anyway who's alive and who isn't. This means there is absolutely no point to the carvings in the sacrifice room, or even to the whole room altogether.

The betting board should have had every possible monster listed on it, given there were dozens of creatures seen that were not on the board but could have been chosen by the five sacrifices in the basement. Also, typical betting pools don't allow for an option of no winner, so every creature should have been bet on by someone or some department.