Preheat oven to 350°F. Prepare popcorn according to package directions. Remove all unpopped kernels. Place popped corn, snack mix, pretzels and peanuts in large bowl.
Stir together Fleischmann's, Worcestershire sauce, lemon juice, garlic powder and onion powder in small bowl. Drizzle over popcorn mixture; mix well.
Spread in 15x10-inch shallow baking pan. Bake 15 minutes, stirring once after 10 minutes. Store leftovers in tightly sealed container.