At the thirtieth minute, the girl walks on the motel outside corridor, the camera shows an empty one, and the second after she pushed Frank who is just about to get into his room. When just before, Frank was about to get into his room, without any girl walking towards him.
It would be virtual impossible to find a motel (especially along a highway) that doesn't have a keycard access on its rooms. It would be so unusual that Amy (Rachel) should have been surprised.
When Dinah takes a drink from the flask, the flask is not open. The cap is still on the flask as she holds it to her mouth.