The car Bryan got into was a 80s Ford Mustang. But the one that exploded was an earlier 70s Ford Mustang II.
When Carol handed him the keys to go home to grab the contracts, it seems to be a whole ring (multi key sounds). However, when Jessica brings Carol home later, she has another key ring she hands Jessica to get into her house.
Detective Sergeant Len Berger tells Jessica that it was a clear cut case of schizophrenia while trying to solve the crimes. This is incorrect, he meant split personality, also known as multiple personality disorder.
In the tennis game at the start, the old man hits a ball high in the air. But the ball appears to hit the net from down low.