When Kate meets Jack in front of her apartment, Nancy says she's cold and is going to wait in the car. A few seconds later Jack walks to the car, which is idling as can be seen by its exhaust fumes, and gets in. The view switches back to Kate and we hear the car start.
When Jack & Kate enter the church and approach the pew, neither one of them genuflected first. Jack asks Kate's neighbor if they may sit with her and they proceed to the pew to sit down.
With each reset, the clock goes from 12 back to 9..., Kate is still on her bed instead of going in reverse (down the stairs and to her previous stop).
The movie is set in New York, but in two scenes evidence that it was actually filmed in Toronto are visible. A Toronto traffic signal (painted amber with amber frame, the latter of which is not found in New York) appears, and in another scene, there are streetcar tracks in the street. New York City currently does not have streetcars.
Kate calls to get her dog back from her ex-boyfriend Jack and the dog lays on the bed with her some of the nights. But on some of the repeated days, Kate presumably does not meet up with Jack but will still have her dog laying with her.