Continuity mistake: When Tess opens the lockbox at the beginning and realises the key is missing, she goes from having her left hand on the box to off it instantly between cuts when she finally gets it open.
Continuity mistake: The first time Tess tries to open the lockbox with the key inside when she gets to the house, the way she is touching/holding it changes between cuts. Specifically, she goes from only having one hand on it to both hands.
Other mistake: When Tess says good night to Keith, the lights in the bedroom are on, but the switch is down (off position) but when she wakes up in the middle of the night, the lights are off and the switch is still down. We see a lamp on the same side as the switch but even if she turned it off manually, being plugged into that AC outlet would mean the lamp would probably be off based on the switch. If the switch was up in both shots, it would be different.