Position and amount of the balls on the carom billiards table in Hall's house changes constantly between shots. Plus, a ball which is first yellow changes color to red and back to yellow. A cue which was not there in previous shots is suddenly on the table and changes positions, too.
When he explores the island, van Weyden's pants change color between shots from khaki with a light brown belt to ecru with a black belt and back.
Aloysius swims to the Kittiwake and enters up, dressed only in shorts. Yet when van Weyden hands him dry clothes and he puts them on, the light pants don't get soaked by the supposedly wet shorts underneath.
When the Kittiwake arrives at the island, the camera focuses from a shot on the ship to a wide shot until the beach becomes visible in the foreground. The waves move away from the shore in an unnatural manner, so does the surf on the beach, revealing the shot to be running backwards.