Actually, Adrian Lyne and talent scouts had narrowed the female leads down to four women which included Beals. They each had their favorite one and could not decide. Lyne brought in a few secretaries from the front office and had them choose. This is straight from Lynes' interview in the 2007 Blue Ray copy. Oddly enough, Beals does not appear in the biography of the film.
In the opening scene when Alex stops to pet the kitten while on her bicycle going to work, she has a construction helmet on the back of her bicycle. A few seconds later, as she descends down the hill, the helmet is not there.
When Alex and her friend are walking home and they encounter street dancers, there is a police car driving slowly in the background. When another dancer steps in the circle, the police car is farther back and again driving slowly towards them.