Plot hole: Fitch should have been aware of Herman Grimes being a selected juror for it was revealed that everyone who received a jury summons for the case was photographed in the beginning of the movie. Herman would have received a summons just the same as the rest and would have been treated the same.
Plot hole: When the lunch was late, wouldn't the bailiff have been wondering why and checking with the restaurant? She knew that the jury was in the room waiting.
Plot hole: The whole point of Marley and Nick's plan was to get back at Fitch, it's also revealed they have been doing this for a while in different cities. There is no way they could know what cases Fitch would take.
Answer: Jennifer Beals' role is a bit of a misdirection towards the viewer, a little like Janet Leigh in "Psycho". It misleads the viewer into beleiving she might be crucial to the plot.