When Jessica follows Ashley out of the office, Ashley boards a city bus numbered 4372. Jessica tries desperately to hail a cab, failing, and ultimately boards a different bus numbered 4226. Fast forward a brief time and Ashley is seen exiting bus number 4226 (the bus Jessica was on), followed by Jessica exiting bus 4372 (the bus Ashley was on).
When Jessica sneaks into Ashley's office, the double light switch on the wall had the left switch up, and the right switch down, and the lights were off. When Jessica peaks down the hall (because she hears Ashley coming), both light switches are up, but the lights are still off in the office. When Ashley comes in, she changes one switch and the office lights go on (but we can't see which switch she changes). When Ashley leaves the office, she flips the right switch down and the lights go off.
When the girl is auditioning (singing) in the theater, the pianist is moving his hands but he's actually not touching any keys.
When Jessica is harassed by the two guys on the street, she hits them with her purse and it is obviously a male stunt performer in a wig.
When Peter Brill is playing the piano at the beginning of the party, his hand movements on the keys do not match the sound of the piano.
When Peter Brill is playing the piano at the beginning of the party, the type of piano he is playing is a grand piano with the top open. You can see that the internal mechanisms you can see moving (hammers, etc.) do not match the sound of the music being played.