Preheat oven to 400°. Place tomatoes in a medium glass baking dish lightly coated with cooking spray. Drizzle with 2 teaspoons oil and a pinch each salt and pepper. Bake at 400° for 15 minutes, until tomatoes are hot and skins are wrinkled. Cover with foil; set aside.
Place 2 teaspoons oil in a large nonstick skillet over medium-high heat. Add mushrooms, and sprinkle with a pinch each salt and pepper. Sauté just until mushrooms are tender and golden brown, about 5 to 8 minutes. Transfer to a plate, and keep warm.
Add 2 teaspoons oil to the same skillet over medium-high heat, along with half of garlic and half of bacon; sauté 30 seconds. Add half of collard greens, and stir-fry just until greens are wilted; transfer to a large metal bowl. Repeat with remaining 2 teaspoons oil, garlic, and bacon, and sauté briefly before adding remaining greens. Stir-fry just until greens are wilted; add to bowl.
Add tomatoes and mushrooms to the bowl with greens. Pour vinegar into skillet (be careful of fumes); simmer 30 seconds. Drizzle over salad, and lightly toss along with salt and pepper to taste. Serve warm.