At about 10:00, Amy is frying something; when the scene starts, she's using tongs, but for the rest of the scene, she's using a spatula.
The movie appears to take place in upstate New York (license plates on cars are New York State, as well as some other American references); but around 21:30 when Maria walks across the road, it's obvious she's walking toward a Canada Post mailbox with a University of Manitoba sign above it.
The motel that Sean and Maria go to shows they have window-box type of A/C, but when they go into the room there are no A/C units under the window.
When she strikes Sean on the head with a bottle, there is no blood on it afterward, despite blood pooling around his head when he falls to the floor.