Kaylene's facial injuries, notably her lip injury, are inconsistent. They are very noticeable, then non-existent, and then clearly visible again.
After the fight for the gun, Drew and Vanessa go over the railing several feet away from each other, yet Vanessa lands on top of Drew.
A police officer would not leave a person that had complained of an attempted murder with the person she had filed the complaint against. If the person was a danger to themselves or others, the officer would take them for a mental evaluation. The reason for this is liability. The officer leaving the combatants together would expose the police to a lawsuit if something happened to the person complaining.
The detective said he was going to call for backup (presumably from local officers that would be closer than he was) well before he arrived at the cabin, yet the backup officers did not arrive until after the danger had passed.
In the car scene with Kaylene and the detective there is a crew member visible sitting in the back seat, obviously to film the shots of Kaylenes phone at certain points. You can clearly see his baseball cap and head bopping around as the car moves. This scene should have definitely been taken again, very poor skills.
Since the other two nurses did not wear ID badges, presumably the facility where Kaylene was treated was a very small facility. Both large and small facilities require employees to wear ID badges to prevent unauthorized people within the facility. At a small facility a woman wearing a nurse outfit that was not known to the two other nurses would have been detected and reported, so she would not have been able to treat Kaylene repeatedly as shown. Additionally, one of the other nurses that was shown being present when Vanessa was treating Kaylene would have been the care nurse, and in the normal course of conversation Vanessa's deceit would have been discovered.
Patients are given follow up appointments after procedures such as Kaylene had. She would have seen a doctor and the excessive prescriptions would have been detected.
Samantha's crash contained several plot holes. First, a large quantity of peanut butter smeared inside the car would have emitted a strong odor which she would have detected and avoided. Second, a person would not have such a sudden reaction to peanut butter residue via skin contact as opposed to ingesting peanuts. Third, she was coherent long enough to stop the car and take her medicine since it was traveling at a fairly low speed in a residential area.
Kaylene learns that Vanessa is wanted while she is at the clinic, but does not call the police until some time later after she arrives home.