Preheat oven to 250 degrees F (120 degrees C). Place butter in a 9x13-inch baking dish; melt in oven while it preheats.
Stir Worcestershire sauce, garlic powder, and seasoned salt into melted butter. Gradually stir rice cereal squares, pumpkin seeds, pretzel sticks, and goldfish crackers into butter mixture until evenly coated.
Bake in the preheated oven, stirring every 15 minutes, until crisp and fragrant, about 1 hour. Transfer party mix to paper towel-lined plates to cool.
