Zac Efron secretly broke his hand filming ‘Gold’. The 34-year-old actor threw himself into his role as a man trapped in a sandstorm in the thriller and though director Anthony Hayes admired the star’s dedication during filming, he only realised the extent once it wrapped. He told the Sydney Morning Herald newspaper that, after the shoot ended, he received an email from Zac containing an X-ray of his hand, which had a metal pin in it after he broke a bone halfway through the shoot but decided not to mention it in case him having treatment got production shut down. Anthony noted: “Once Zac got o…