Continuity mistake: During the scene in which the two main characters are diving, before the boat leaves them, Susan's snorkel swaps from the left side of her mask to the right and back again.
Continuity mistake: In one scene where the husband looks under water to see where the sharks are he gets startled and raises up out of the water. As his face comes up he removes his mask. The camera angle changes and in the next shot you see him removing his mask again. (00:50:20)
Continuity mistake: When Susan and Daniel are in bed, Susan puts her glasses on the table then turns around, and her blanket changes position between two consecutive shots. (00:07:30)
Continuity mistake: When Susan and Daniel are making out in bed she starts laughing and says "Nice face." You can see Daniel's nose is clean. When it cuts his nose is covered with face mask stains from Susan's face. (00:07:55)
Continuity mistake: When Susan says "I'm just gonna look, OK?" she puts the snorkel in her mouth, however in the next shot underwater, she has the regulator in her mouth, not the snorkel. (00:33:35 - 00:34:10)