Place a large, rimmed baking sheet (at least 17 x 11 inches) in oven; preheat to 425°F. (Do not remove while oven preheats.) Unwrap pizza dough, and cover with a kitchen towel. Let dough stand while oven preheats.
Meanwhile, cook ground beef in a large nonstick skillet over medium-high, stirring often, until meat crumbles and is no longer pink, about 7 minutes. Sprinkle with salt and pepper. Remove from skillet with a slotted spoon, and drain on a plate lined with paper towels.
Add mushrooms to hot drippings, and cook, stirring occasionally, until light golden, about 5 minutes. Add onions, and cook, stirring occasionally, until softened and beginning to brown, about 4 minutes. Remove mushrooms and onions with a slotted spoon, and drain on paper towels.
Roll dough into a 17- x 11-inch rectangle. Remove preheated pan from oven, and carefully place the dough onto the pan.
Bake in preheated oven just until dough is set, about 5 minutes. Remove from oven, and top with pizza sauce, beef, mushroom-onion mixture, shredded cheeses, and olives. Drizzle with ketchup.
Return to oven, and bake until crust is golden and cheeses melt and begin to brown in places, about 15 minutes. Let stand 5 minutes before slicing.