Johnny Depp shot all of his scenes in eight days, but after filming was done he didn't want to leave. So he suggested to Robert Rodriguez that he play a small part, the priest that Antonio Banderas talks to in the church, and used his Marlon Brando impression.
The man Barillo hires as a body double was an assistant. There were no digital effects. The man looked as identical to Willem Dafoe as he did in the movie.
It was Johnny Depp's idea for Sands to wear tacky T-shirts. He even sent his sister to Florida to find the tackiest ones from tourist stalls.