the render looks very nice!
but the cars in the background(31, 83 and maybe 81) doesn't follow the "plane", so those looks like, like those follow a curve not a flat thing, maybe the camera angle made that view to me, realy don't no, but something wrong with it i think, sorry
I know what you meant
I have the same problem when I render a photo as background,
you don't look in the depth,
has complied with the angle or lens of the camera to make.
I have not yet found how to resolve.