Heat a large Dutch oven over medium-high heat. Add the vegetable oil and popcorn kernels and cover the pot. Cook, shaking the pan every so often, until all the kernels have popped, about 5 minutes.
Drizzle the popcorn with the melted butter and sprinkle with the salt; toss lightly. Transfer to a rimmed baking sheet. Drizzle with the melted chocolate, then sprinkle the candy-coated chocolate candies, nonpareils and mint chocolate candies over the top. Let sit for 30 minutes to allow the chocolate to harden.