Visible crew/equipment: In the last scene where the main character escapes, he jumps into the bay and is supported by a sack which he is carrying. Actually you can clearly see that he is supported from underneath by a diver.
Continuity mistake: In the scene where the inmate is being beheaded in the courtyard, as they change shots for the special effect you can now see that the sun has moved and is glaring into the camera lens and the executioner is now visible standing next to the guillotine.
Continuity mistake: Just after Papillon tattoos the butterfly on the native, he walks away with a considerable amount of sweat on the back of his shirt. A shot or two later, as he is walking toward the hut, most of the sweat has disappeared.