Destructo in flight.
Not a spy gadget in the usual sense but a remote-controlled, flying, explosive toy bomb for sale at Bowers Department Store.
When Maxwell Smart and Agent 99 find themselves unarmed and trapped in the store's toy department, they resort to using the toy weapons on display there and discover that the playthings - especially Destructo - are more devastating in their effect than their would be captors' real guns and bullets.
[Episode #4: "Our Man in Toyland".]