Dwayne Johnson Spencer Jack Black Bethany Kevin Hart Fridge Karen Gillan Martha Nick Jonas Alex Bobby Cannavale Van Pelt Ser'Darius Blain Young Fridge Madison Iseman Young Bethany Morgan Turner Young Martha Alex Wolff Young Spencer Rhys Darby Nigel Mason Guccione Gamer Marin Hinkle Spencer's Mom Tracey Bonner Fridge's Mom Natasha Charles Parker Bethany's Mom Maribeth Monroe Teacher Missi Pyle Coach Webb Marc Evan Jackson Principal Bentley Carlease Burke Miss Mathers Jason New Bivouac Biker William Tokarsky Bread Vendor Rohan Chand Kid at Bazaar Tait Fletcher Scorpion Recipient Stephen Dunlevy Transportation Shed Guard Danny Pardo Bazaar Vendor (uncredited)