There's no scar on the bridge of her nose in the police interview when she clearly has a major cut there from her felon encounters. Unless it's been a year and plastic surgery, there will be something there.
It is said that a couple died due to carbon monoxide (a product of combustion) because the stove gas was on all night. While gas can suffocate like CO, the stove would have to be lit to produce CO.
When Kayla uses a knife to cut the tape on Ty's wrist she does so in a stupidly unsafe upward manner, which would have stabbed the poor kid in the face had it not been a prop weapon.
When Becky jumps off of the cabin roof to knock down her momentarily-distracted assailant, he drops his handgun. Becky then stabs him several times with a broken, sharp-edged wooden ruler but inexplicably ignores the handgun which she could have used later--an obvious missed opportunity.
When Becky wipes the blood of her face, about 50 minutes into the movie, the blood does not smear nor does it wipe off.
At the end of the film, Becky openly possesses an object that Kayla surely would have told the police was a key clue to Dominick's crimes, yet they don't take it or even ask her about it. Even if Kayla omitted that info, the cops should have noticed the design on the object matched one of Dominick's tattoos.