AMSTERDAM — Families enjoying a free movie in Veterans Park on Wednesday night were rattled by the sudden firing of two gunshots by a male involved in a dispute in the park.“It was completely unexpected,” John Tirelli said Thursday. “The idea they brought a gun there, just really, there is so little thought for anyone but that individual’s self. It’s really unfortunate.”Calli Elliot and Tirelli were at the family friendly screening of “Minions: The Rise of Gru” with their two kids, ages 4 and 13.The family was engrossed in the movie when Tirelli heard a “popping” sound and began looking around.…