'Gadar: Ek Prem Katha,' even 20 years after its premiere, has remained a classic. The romantic period action film was notable for its authenticity, as it was shot on location in North India. A team studied historic locations, did a recce, and picked props from the era they were replicating before the film went into production. And, although filming in real locales, they made significant alterations to give the film a pre-independence feel.