The theme: The correct answers to the major clues were incomplete common expressions. Within each is a circled letter (or, in one case, two circled letters) that completes the expression. For example, 36 Across, the clue: Hans Christian Andersen story; the answer: The Princess and the — “P” is in the circle.
Have you ever heard of the island of Sauai? Well, me neither. But according to the clue, it is “‘the wettest spot on Earth (450+” of rain per year).” A bit of trivia that I suppose could come in handy if one ends up on Jeopardy.