When Rockford arrived at Barry Silverstein's office music was playing from the reel to reel tape deck and it was turned off. As Rockford was leaving, the camera panned past the tape machine and there was no reel of tape on it, even though no one ever went near the machine to remove the reel.
As Jim is driving, he notices in his rear-view mirror that a car is right on his rear. The view changes to an outside view of his car as he comes to the end of a street. The view is of his car and a whole block, but with NO one on his rear, and with NO one even behind him. The view changes to inside of Jim's car again and he sees that car in his rear-view mirror again and right on his rear.
It's an age-old misconception that poison ivy, poison oak, etc. can be spread by physical contact with an infected person; you have to come into contact with the plant's oils.