While filming in London in October 2010, Johnny Depp received a letter from a local nine-year old schoolgirl, telling him her classmates needed help to "mutiny" against her teachers. He turned up with almost no warning at the school in full Captain Jack Sparrow outfit, but advised against mutiny.
After Walt Disney's chairman of thirty-eight years, Dick Cook was fired, Johnny Depp talked to the Los Angeles Times, and said his enthusiasm for the fourth Pirates movie had reduced after Cook left the project. "There's a fissure, a crack in my enthusiasm at the moment", Depp said. "It was all born in that office." One of the reasons Johnny Depp committed to La maledizione della prima luna (2003), was because he trusted Cook, who supported him while "others at the studio were less than enthusiastic about my interpretation of the character, Dick was there from the first moment. He trusted me."
Johnny Depp bought new water proof jackets for five hundred crew members on the set, to protect them from the cold weather. He spent a total of sixty-four thousand two hundred dollars from his own pocket.
Penélope Cruz was pregnant throughout production, but it wasn't noticeable until September 2010. As Penélope's baby bump grew, it caused difficulties in wardrobe, so the producers enlisted the help of Cruz's younger sister, Mónica. According to reports, Penélope filmed the close-up shots, while Mónica doubled for her in the long-distance scenes.
During filming in London, a Captain Jack Sparrow impersonator just walked onto the set. The guards did not think to ask for any ID, as he looked so much like the character (as reported in the English papers).