Plot hole: The giant-sized teenagers show themselves at the garden party and start making threats about taking over the town. They then spend the night in the theatre, and the next day they decide to cut off all communications to and from the town. For some reason, not one of the party-goers, or the sheriff, decided to call someone during the night and tell the remarkable story about 30 feet tall teenagers seizing the power through force.
Plot hole: Before the race starts, Sir Percy intends to sabotage some of the other fliers. He announces to Courtney that he had lured Dubois away by giving him the address of Courtney's daughter, but later, when the race starts, there is nothing wrong with Dubois' machine even though Sir Percy had the chance.