When Jim is eating "greasy" chicken with Mr. Bannister after Mr. Bannister has said, "and she has refused to do so" and Jim replied, "right again", the next 4 words supposedly from Mr. Bannister ('all right, Mr. Rockford') are dubbed by someone else, someone who doesn't sound anything like him.
In the opening pan of Rockford's desk while the answering machine is playing, you can see someone resting their left hand on their leg (wearing boot cut blue jeans and cowboy boots) between the picture of Rocky and the close up of the telephone.