The mystery and its solution was a great noir conceit. I do have some questions though, maybe I wasn't paying enough attention.

Who killed the neighbor and why? Who killed the replacement girl and why?

And some minor quibbles, they should have shown the stopoff at the hotel for the switch. Not that they should have shown the switch, but they should have shown Jim and the girl going in the hotel, Jim going to the bathroom, coming out and being told by the bartender that his girlfriend went to the car without him.

then, Jim getting back in the car and seeing the sleeping woman, and little girl in his back seat.

This would have given the viewer a sporting chance at figuring out the solution.

I wish I taped it though, I'd like to see it again.