I saw this very strange movie in the theaters when I was a kid. I was born in 1990 so it must have been released in the mid to late 1990s. It was in color and was about these kids who were imprisoned in an underground factory maybe shoveling coal? They were enslaved and held captive doing some odd job. The protagonist was a kid who somehow found all these other kids and was forced into this pointless pursuit. I vaguely remember something about tomatoes and candy bars as having something to do with the plot. It was a very surreal and quirky movie. Any ideas?