When the pickup truck first crashes in the water, it stalls and the headlights go out. In the next scene, they are on again. Besides a continuity error, this implies an unusually waterproof electrical system.
When Jody visits Claire and brings her the mushroom tea they are sitting on the porch facing the parked cars in the driveway. When Jody gets up and sits on her new car to show it to Claire, Claire acts surprised as if she's seen it for the first time.
Claire first sees the ghost when she reaches out to pull the plug from the bathtub. She screams and Norman runs in. She hugs him, and puts her hand on the back of his robe. Her hand isn't wet, and his shirt doesn't get wet.
It seems unlikely that Norman or Claire would be able to dial 911. Only 30 of Vermont's 250 towns have 911 service. Residents in rural areas, like Norman and Claire's town, have to dial 7 or 11 digits to call for emergency services.
Adamant, Vermont is mentioned twice. Both times it's described as being "down 7", meaning southward on US Route 7, the principal north-south artery on Vermont's western edge. Route 7 passes through the Burlington/Lake Champlain area where the movie is set. Adamant is about 40 miles east of Route 7.
When Claire's friend visits her early in the movie, she brings her a pouch of "Kombucha mushroom tea". Kombucha has been used in Europe for centuries, and gained popularity in the U.S. in the 1980s. It's black tea semi-fermented by the kibosh fungus, which floats on the top of the tea, growing thicker as it eats the tannins in the tea and the sugar that you add, producing the distinct "zingy" taste of kibosh after 2 to 4 weeks. In the movie, it's portrayed as a simple dry tea, not a disc-shaped commensal colony of bacteria and yeast. that must be kept alive.
The picture that keeps breaking is a newspaper clipping of the same celebration that Madison attended. While the clipping reports the search to be "intensifying" and Madison didn't go missing for three days, the report could have been from a weekly newspaper.
When Claire finds the tub filled with water (both times), it is
completely filled. While the overflow drain would not have normally permitted this (and while the second time, it has filled abnormally fast and quietly), it's a ghostly event, which means some of the normal laws of nature are suspended.
When Claire is looking up missing persons and comes across Madison Elizabeth Frank, her details are to the left of the screen and her picture is to the right. When she hands the page to her husband, the picture is on the left and the info is on the right. The page may have had a "format for printing" option.
When Norman falls in the bathroom, he opens a large gash on the right side of his forehead. Later, when the pickup plunges into the water, the bloody gash is visible during the fight scenes. In the last few shots of Norman underwater, the gash disappears.