Tie-In Puzzles

Tie-In Puzzles are puzzles either found in outside publications that are then required to solve a puzzle during a hunt (along with those hunt puzzles themselves) or puzzles that hide information required to solve said puzzle in a piece of outside media.

Background
The earliest case of a modern puzzlehunt utilizing a tie-in puzzle is the 1994 MIT Mystery Hunt, wherein the first puzzle of the hunt simply told solvers to complete that day's New York Times crossword puzzle, with important information reading down the first and last columns of the grid (all explicitly mentioned in the description of the hunt "puzzle"). Since then, however, tie-in puzzles have evolved to being more than just a redirect to an outside source, as well as having increased range of media used. This is likely due to the diversification of individuals writing the hunt, as a larger writing team increases the chances of the team having at least one person with the connections to make certain tie-ins possible.