Destroy All Monsters! (1968)

Those wacky Japanese folk have exiled all the world's giant beasties-who-are-totally-not-dudes-in-rubber-costumes (Godzilla, Baragon, Mothra, Rodan, Gorasorus, &c.) to a remote island imaginatively code-named "Monsterland." (And what a dump compared to that swanky Skull Island, no turn-down service or anything, but I digress.) Undoubtedly cutting short plans to open a theme park featuring Jeep safaris -- See the Monsters in their Natural Habitat!! -- some no-good Kilaaks swoop down from their secret base on the Moon, and set all the creatures loose. Before you can say "Toho" the liberated beasts are smashing up cardboard replicas of London, Manhattan, Tokyo, Peoria, you name it. This is all part of the Kilaak's plan for world domination, right up until the beleaguered Earthlings invent broadband wireless and regain control of "their" monsters. A showdown with Ghidrah (representing the Kilaaks) atop Mt. Fuji decides the Ultimate Fate of Mankind. For all their troubles saving Earth from alien invaders, our conquering heroes are promptly sent back to the critter ghetto that is Monsterland. What's the lesson here?