Inevitably, a ball will be dropped. As humans we are not perfect, and details (large or small) will fall through the cracks. A sinking feeling will accompany the realization that something has been missed.
After the fact, you can only issue damage control. Salvage what remains and make the best of a situation. But as future projects and tasks are assigned, realize the details that are mission critical. If a ball is going to be dropped, make sure it's not the game-winning or game-losing point.
As more irons are added to the fire, your focus can only be spread so wide. Instead of doing a mediocre job in numerous areas, focus on the priorities. In the end, find what is most important to your leadership, and ultimately the organization. Keep your eyes on those details first, and budget your attention to everything else later.