Sauté bacon, bell pepper, onion, and garlic in a large skillet over medium heat until bacon is cooked and onion is translucent, 8 to 10 minutes.
Mix in corned beef hash and mushrooms. Season with salt and pepper. Cook, flipping sections of the hash occasionally, until browned, about 10 minutes.
Meanwhile, whisk eggs and milk together in a small bowl. Once corned beef hash is near done, pour egg mixture into the skillet. Cook, stirring occasionally, until eggs are cooked and no liquid remains, 3 to 5 minutes.