Maxine's blue eye shadow has washed off after swimming in the lake, but it's fully reapplied as she enters the farmhouse, despite her not stopping to reapply it.
When Wayne is looking through the holes in the barn, his face is a ways away from the wall. But when he gets stabbed it's much closer, with his nose almost touching it.
When the crew stops at the gas station there's a slow shot of Maxine closing the backdoors of the van but the very next shot shows her closing the side door while Jackson and another character are closing the backdoors of the van.
Wayne uses the term " Home Video " which is not appropriate for adult movies in the year 1979.
The film is supposedly set in 1979. The film crew's van has Texas 1974 license plates. They should be 1975 or later with validation sticker, up to 1974 new plates were issued annually.
When Lorraine enters the basement and turns the light on, there is a modern halogen light bulb, which was not available in 1979.
About 1hr 24 minutes, the old man turns on the TV, the picture comes up immediately. With these old CRT TV's it took a minute or so for the tubes etc to warm up before anything came up on the screen.
The police cars are mostly Chrysler K platform, but those were not released until 1981. Aside from being impossible to get in 1979, an impoverished rural county would not get such vehicles until the mid to late 1980s at least.
Early on, whilst in the gas station, Wayne says several words without his lips moving.
At the beginning of Maxine's "Farmers Daughters"-scene shoot in the cow barn, Bobby-Lynne slams the clapperboard so softly, that it's basically impossible to sync up the sound in post, rendering that take useless.
At the end, the police handle the camera without wearing gloves, potentially destroying fingerprint evidence.