This episode takes place in 1978 but Devil's Island was closed down in 1953.
As Mr. Roarke goes to meet Ann and Maxine by the pool he stops after he passes the camera as the shadow of his head remains visible in the lower right as Tattoo talks to Dr. Roger Sullivan.
John Saxon (Roger) says he saw a green hat to wear to the fancy dress party. When at the fancy dress party his hat is a brown/reddish colour.