At the beginning when Professor Payne (Jay Mohr) barges into Melinda's house, Jim (David Conrad) opens the door and Payne pauses briefly in the entry way to say a few words to him. During this pause, you can see the two men are practically nose to nose - clearly no difference in height. But according to their IMDB profiles, David Conrad is 6' 1" tall while Jay Mohr is 5' 9" tall. A 4 inch difference in height should be quite noticeable.