Revealing mistake: Kate's birthday is July 10th. When she is (with long hair) outside on the patio with Alex, you can see their breath as they talk, and there is not a living thing in the back yard, it's all dormant (as in late fall/winter).
Revealing mistake: When Kate kisses Morgan in front of 1620 N. Racine, the camera moves up through the branches of a tree. You can see one of the lower branches shake when it is bumped by the crane. (01:17:20)