The Spanish Prisoner

The Spanish Prisoner is a suspense/crime/mystery film written and directed by David Mamet. It revolves around Joe Ross, a researcher for an unnamed major company who's recently perfected an unspecified process which is worth a great deal of money. While on a business trip in the caribbean, he meets and befriends a wealthy traveller who offers to advise him and help him get a fair share of the profits. Shortly, however, he begins to question his new friend's motives and intentions. As in most Mamet stories, deceptions and cons pile up as both the protagonist and the audience try to figure out who's telling the truth, and who's part of a plot.

Tropes used in The Spanish Prisoner include:

Chekhov's Gunman: In multiple scenes throughout the movie, there are Japanese tourists in the background taking pictures. Everyone ignores them, in the end they turn out to be Federal Marshals who were following the whole plot.
Chekhov's Caugh: Joe's best friend, a lawyer, gets a cold that follows him throughout the movie. Subverted when he is found stabbed to death in the second act
The Con: Joe spends the whole film trying to figure out what con he's been a victim of. The titular "Spanish Prisoner" con is but one of many.
Didn't See That Coming: Almost everything that happened was planned out, but the plotters didn't predict that Joe would just happen to hang on to a book that one of them left fingerprints on.
The Ending Changes Everything: By the end of the film, it's clear that almost literally no one but the protagonist has been telling the truth about anything. The whole thing has been a con within a con within a con.
Foreshadowing: Early on, Joe sees a boat moving from a seaplane towards the shore. Susan points out that he never actually saw the boat leave the plane, it could have been coming from anywhere "and we have no idea who anyone is."
It Was Here, I Swear: Joe leads authorities to Jimmy's "office" which is empty.
Massive Multiplayer Scam
McGuffin: The "process", about which we are told absolutely nothing except that it's worth a lot of money.
Meta Twist: Mamet must have known that the audience would be expecting a con game to turn up in this film. We hit that twist and the con is uncovered and explained before the movie is half over. Then we realize that we haven't uncovered anything yet.
Police Are Useless:
- In fairness to the police, things were deliberately set up so that Joe would look guilty and half of his story fell apart on inspection. Naturally they don't believe his pleas of innocence.
- Then subverted when we find out that Federal agents were following the case from the beginning.
Out-Gambitted: The plotters had a brilliantly detailed and multi-layered plan to get ahold of the process and leave Joe to take the fall. In the end the Feds were watching them the entire time and were just letting them proceed to gather evidence.
Spanish Prisoner: The Con for which the movie is named. The film includes a detailed explanation of this con, the purpose of which exposition is to disguise the fact that it is not the con being performed.
Undercover Cop Reveal: Joe is saved at the end by Japanese tourists who are in actuality U.S. Marshals.