The Story: Sixty full years after a devastating alien invasion in 2017, surviving humans patrol post-apocalyptic Earth - defending geo-thermal energy generators that power the "Tet": an advanced space craft scheduled to relocate humanity to Titan (one of Saturn's moons). As humankind continues ongoing preparations for an interplanetary trek aboard the Tet, Jack Harper (Tom Cruise) and his partner Victoria Olsen (Andrea Riseborough) scan a sector of Earth (from their home Tower 49) for hostile lifeforms known as the Skavs - destructive extra terrestrials that stayed on Earth following the initial invasion (six decades before). Guerrilla fighters, the Skavs are determined to disrupt power to the Tet - in order to prevent humanity's exodus from Earth.
The Spoiler: The Skavs are actually humans.
The Trailer: The Oblivion trailer makes it apparent that the Skavs are not aliens - they are human freedom fighters waging a guerrilla war against an unseen force. Led by Malcolm Beech (Morgan Freeman), the Skavs explain that Harper has been manipulated by their enemy - and is, unknowingly, working against the survival of his fellow humans. Thankfully, the Oblivion trailers refrain from spoiling one of the film's biggest twists, e.g., Harper, Olsen, and the Tet's backstory but, with the reveal of the Skavs's identity, it wasn't hard for savvy sci-fi moviegoers to fill in the remaining puzzle pieces ahead of director Joseph Kosinski.
The Story: While attending a science fair, ten year-old Sean Mullen (Brawley Nolte) is kidnapped by a group of well-organized criminals - who demand that millionaire airline chairman Tom Mullen (Mel Gibson), and his wife, Kate (Rene Russo), pay $2 million in cash for the boy's safe return. Mullen is counseled in the hostage negotiations by NYPD Detective Jimmy Shaker (Gary Sinise) - who advises the increasingly concerned father that the best way to ensure Sean's safe return is to keep a calm head and pay the money. Under the advisement of law enforcement officials, Mullen agrees to a ransom drop; however, when he arrives at the drop point, the kidnapper is unable to provide Sean's location - causing Mullen to question the best option for Sean's safe return. Taking matters into his own hands, Mullen refuses to hand over the cash - devising his own (arguably risky) plan to find and protect his son.
The Spoiler: Mullen turns the $2 million ransom into a $2 million bounty.
The Trailer: In order to position Ransom as a deviation from standard kidnapping thrillers, the studio put a heavy emphasis on Mullen's unorthodox approach to finding Sean - outright spoiling one of the film's most interesting developments (as well as several tense standoffs that precede it). Instead, the trailer plays coy with another twist, one that is revealed in the first 15 minutes: Gary Sinise's Detective Shaker is actually the film's primary villain/hostage taker.
The Avengers (2012):
The Story: Long before Captain America (Chris Evans) and Iron Man (Robert Downey Jr.) will go head-to-head in Marvel's Civil War storyline, the two were already at odds during The Avengers - leading Steve Rogers to accuse Tony Stark of being a narcissist (and incapable of sacrificing his life for others). Proving Rogers wrong, Stark puts his own life on the line when he intercepts a nuclear rocket headed for New York City and flies the bomb, on a one way trip, through the Tesseract portal into uncharted Chitauri space. Depleted of energy during the Battle of New York, Stark goes dark and drifts back through the collapsing portal - in an uncontrolled descent to Earth (with nothing but the ground to stop his fall).
The Spoiler: Hulk catches powered-down Iron Man.
The Trailer: After "killing" Agent Coulson to galvanize the superhero team forward, it was unlikely that another key Avenger would fall in Marvel's first multi-hero team-up film; yet, director Joss Whedon played-up Stark's scene of sacrifice as if it were a real possibility that the Avenger might not make it back to Stark Tower (and Pepper Potts) alive. Unfortunately, The Avengers trailer undercut any potential suspense, since it included a memorable shot of Hulk successfully leaping into the air and catching a powered down Iron Man, which sucked any tension out of the film's climactic moment (at least for anyone who bothered to watch the preview more than once).
There are plenty of movie moments (and twists) that were spoiled by their trailers but here are few more that we wanted to highlight:
The Double (2011) - Richard Gere is actually the villain.
The Grey (2012) - Wolf battle royale.
How to Train Your Dragon 2 (2014) - Family reunion.
Snowpiercer (2014) - Every train section revealed.
Terminator 2: Judgment Day (1991) - Arnold is the hero.
As mentioned, our list is not all-inclusive, and we're interested to hear which movie moments were spoiled for you by trailers. Share your picks in the comments!