Mice are a pretty big issue in many restaurants and kitchens. Other pests that might be an issue include cockroaches.
The customers who constantly complain, the customers who want things for free, the waitresses who are on drugs, and the cooks who aren't paying attention to the modifiers on food.
Selection of furniture! This is a whole quest that you need to go through because it is so difficult to calculate what size kitchen cabinets you need, and then find the ones you need and looks pretty. We gave up and turned to https://kitchensearch.com/ to immediately fit everything into our custom kitchen.