The third time Mac tries calling Enright, the window behind him shows daylight but it was already established that it was dark out. The same daylight is seen behind Sally later, when she turns down Mac's invitation to spend the night in a hotel.
When Mac plays a record on the gramophone, it's Sally's manicured hand that is shown next to it - they re-used a shot from when she had played the record earlier.
While drinking champagne in Enright's car, Loretta's glass changes from full to empty when the camera angle changes.
While Mac is pouring the drinks after noticing the corkscrew and bottle opener are missing, the moving shadow of a boom mic is seen on the wall behind him. Visible off and on throughout the scene.