I'm trying to identify an animated movie I saw in the theater around 1980. It was a children's matinee, so it may be older. In the movie, a boy visits an island or city where the inhabitants are all androids or robots. The island may have been operated or built by his relative... an uncle? Things go wrong, and he has to escape, chased by everyone.
The twist at the end was that as the boy was floating away on a boat, he started repeating himself like a broken record, thus revealing himself to be an android/robot also.
The only line I can remember from the movie was during the chase, when the villain shouted he was going to turn them into shish kebabs. Googling that phrase hasn't turned up any hits that I recognize.