The production unexpectedly ran out of money halfway through and halted for several months in order to find new investors. This ended up working in its favor, since the young lead actor
Marcell Nagy was going through puberty, and by the time they restarted he looked physically more mature, taller, and his voice deeper. By the time his character enters and survives the death camps he looks years older than when the film began, adding an element of reality that otherwise would have been created with make up
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