Ant-Man

Dr. Hank Pym, the original Ant-Man, (played by Michael Douglas) is trapped with his daughter in a building that is about to be destroyed.  They have no escape until Hank reveals that his tank keychain is more than it appears.  They burst through the walls of the building using the keychain because it was actually a real tank that he had shrank earlier.  Even the keychain part is expanded.  His keychain can be seen several times throughout the movie.  And in the early footage of the original Ant-Man that is shown a tank that looks very similar can been seen.  One must assume it is the same tank.

Payback

The head of the outfit gives his son a car for his birthday.  He presents him with the key and an engraved keychain.  Porter, played by Mel Gibson, taunts the mob boss with the knowledge that he kidnapped his son.  He offers to read him the inscription on the keychain and calls it sappy. 

A History of Violence

In the opening of the movie, two mobsters are on the run trying to lie low in small towns.  They are leaving their motel and their blue rabbit's foot keychain can be clearly seen. 

Mortdecai

Mortdecai, played by Johnny Depp, is trying to escape from someone trying to kill him.  He takes a car from his mechanic's while his man servant, played by Paul Bettany, holds off the assassin.  The keychain is the type in which a metal medallion is attached to a piece of leather. 

The Machinist

Trevor Reznik played by Christian Bale confronts the man who he thinks is behind a plot against him. His leather fob keychain can be seen.

Thief

In preparation for the upcoming heist Jim Belushi's character, Barry, is listening in on the owners of the safe for a password to turn off the alarm.  The owners of the safe open their front door and their keychain can be seen.  This type of keychain is hourglass shaped with a metal circle on one end.  There is a notch in the circle where the key is threaded onto the metal bar.

Mission Impossible Rogue Nation

In the beginning of Mission Impossible: Rogue Nation, Ethan Hunt is captured.  The literal key to his escape is on a rabbit foot keychain.  This is most likely a reference to Mission Impossible 3 whose plot centered around the mysterious "rabbit's foot". 

Sex and the City

Charlotte and her ex-mother in law, Bunny, are fighting over her apartment during Charlotte's divorce.  Bunny shows off her keys as proof of her ownership of the apartment.  Bunny has a solid metal bunny keychain.  Quite appropriate. 
From season 5 episode 5

Everybody Loves Raymond

Debra And Raymond are staying at a bed and breakfast to have a romantic weekend.  The bunny keychain on the room key is indicative of the cutesy theme of the bed and breakfast (much to Ray's dismay).

Supernatural

Supernatural has MANY keychains featured over the course of the long running show.  This first keychain is Dean's which is a bullet, it of corresponds nicely with the guys' lives as hunters.  It can be seen several times throughout the show.  This screen cap is from season 5 episode 18. 

From season 1 episode 15

From season 1 episode 16

From season 5 episode 14

From season 4 episode 7   The show features many keychains from the motels and hotels the guys stay at.

From season 14 episode 4   Toys are coming to life and trying to kill a comic book shop employee.  Sam and Dean figure out a ghost has attached itself to the keychain of the shop.  They dispatch the ghost after it inhabits a life size replica of a slasher villain.

Fantastic Four

In the trailer for the upcoming movie Fantastic Four, there is a very telling keychain.  On the rear view mirror of his car, Johnny Storm aka the Human Torch played by Michael B Jordan has a fire flower keychain.  The fire flower being the classic power-up from Super Mario Brothers.  Not only does this reference the human torch's power to control and emit fire but it represents the fact that this Fantastic Four is made up of younger people. 

Cast Away

Chuck Noland (played by Tom Hanks) has a swiss army knife keychain.  Right before his ill fated plane flight he gives Kelly (helen hunt) an engagement ring and his keys.  When he finally returns home she gives him the keys back.

The Hunter

William Dafoe's character, Martin, is just getting his assignment to hunt the, thought to be extinct, Tasmanian Tiger.  A key with a keychain can be seen as he going through his belongings.  It is a silver circle with the number 53 stamped on it.

Hook

Peter Pan (Robin Williams) visits tinkerbell at her home,  which is a cuckoo clock.  She has his personal possessions all around her including his keys and BMW keychain.

Z Nation

Murphy is desperate to get to California due to his worsening condition.  He tries to steal someone's car by biting them and taking their keys.  The man kept talking up his car and its upgrades while drunk in the bar earlier.  His skull key and paracord keychain matches the description of the ride.  From episode 7 Welcome to the Fu Bar.

The gang is using a white van which has a basic pink/purple fob.  Murphy steals the van, which is full of valuable oxycotin, at the end of the first season leaving everyone else to die.  From Episodes 12 and 13.

Criminal Minds Season 1 Episode 1 Extreme Aggressor

The real villain's keychain is revealed just as he is.  It is a metal z which represents his car.