Revealing mistake: Jack did not rip Elizabeth's corset, as the sound effects suggest: the bustier's hooks were all already undone, and he just pulled the different pieces aside. (00:16:15)
Sereenie
Revealing mistake: When Elizabeth falls down from the cliff, with her hat and scarf falling over her, you can see it is definitely not Keira Knightley, as the stuntperson's face is perfectly visible. (00:15:05)
Continuity mistake: When Jack walks down the dock to the Interceptor, Murtogg and Mullroy are sitting with sacks, crates and barrels in a deep shadow, but the sun is seen afar. A few shots later, after they intercepted him, those same sacks, crates and barrel are brightly lit by the sun. The shots were probably filmed at different times of the day. (00:11:45)
Visible crew/equipment: In the extreme close up of young Elizabeth's face, when she first sees the Black Pearl, the only things in front of her are 1) sky; 2) sea; 3) Black Pearl. Yet, in her eyes are reflected two big, round objects - filming spots or reflectors. (00:04:45)