Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking pan.
Mix cake mix, water, oil, and eggs together in a bowl; pour into prepared baking pan.
Bake in the preheated oven until a toothpick inserted in the center of the cake comes out clean, 28 to 30 minutes. Immediately poke holes in the cake using a skewer or straw.
Pour sweetened condensed milk, hot fudge, and caramel over cake. Allow cake to cool, about 1 hour.
Spread whipped topping over cooled cake and sprinkle with crushed peanut butter candy. Refrigerate until serving.
