MIT Mystery Hunt 2020/Change Machine

Change Machine is a variety puzzle from the round of the 2020 MIT Mystery Hunt.

Puzzle Elements

 * Green Eyes, Take Warning - This puzzle uses color—especially with regards to the colored numbers on the reverses, which can be red or green.


 * Image-Heavy - The body of the puzzle contains the obverses and the reverses of twenty-three "coins". The reverses are a number of images with red, green, or black numbers on them,...


 * Clue-Centric - ...while the obverses feature crossword clues (with numbers labeled KJ and MP).


 * Audio - In addition, there are twenty-three audio files, each one containing a reading of a line of text and a "T number".


 * Flavortext - We finally opened the time capsule we'd unearthed, but inside was just a note, saying "Sorry, took the tokens to play in the arcade" and descriptions of the tokens. Images of the token faces and an audio recording obtained from the tokens' edge grooves were included, but we couldn't determine the correspondence between obverses, reverses, and edges.

Also included was a cryptic note that looked like this:

MP: T: KJ: Key +/-:


 * Identification (Film) - The reverses are all parts of movie posters; identify the movie.


 * Identification (Religion) - The audio files read out verses from the King James Bible.


 * Knowledge Required (Other Media) - Looking up a number of the objects identified in the obverses or a number of the films referenced in the reverses will pull up pages about the Omnibus podcast hosted by Ken Jennings and John Roderick (which describes itself as a time capsule).


 * Association - Each podcast episode has a title (obverse), a related film referenced using its MPAA certificate (reverse), and an ID that makes reference to a verse from the King James Bible (audio). The three data streams can now be associated with each other.


 * Indexing - Following the order from the cryptic note, the solver should index into the film title using the MP number from the obverse...


 * Reordering - ...which asks the solver to ORDER REST BY EPISODE NUMB[er]S.


 * Indexing - After reordering, the solver can now index into the episode title using the T number from the audio file and the verse using the KJ number from the obverse.


 * Tie-In Puzzle - The phrases obtained this way are EPISODE NUMBER TWO TWO FOUR / AD AMUSEMENT COMPANY IS KEY. Solvers must now reference Episode 224 of the Omnibus Podcast (which was released the Thursday before hunt) and listen for an ad. Sure enough, at around 14:10, an ad is read out for the RIDE ENHANCERS COLLECTIVE, a company related to amusement parks with a suspicious 23-letter-long name.


 * Caesar Shift Salad - This string can be shifted letter-by-letter using the colored numbers on the reverses as keys (using typical red-negative color connotations) to obtain the answer.