In Ben X, Ben's online girlfriend Scarlite actually left the train station without recognizing him; the version of her that kept him from killing himself and helped him develop his plan was a hallucination.
In the horror anthology film Body Bags, John Carpenter's character the Coroner, who hosts the wraparound segments, initially seems to be just an intensely weird mortician. There are several hints dropped throughout his parts, including his consumption of the lethal chemical formaldehyde and his lifeless, pale skin, but it isn't revealed until the very end that he's actually another corpse who assumed the role of the real morticians.
In Cypher, the protagonist Morgan Sullivan is in fact the legendary spy Sebastian Rooks, which Rita Foster knew all along because she helped him plan the whole thing.
Identity, starring John Cusack. The main characters are all the selves of a man with multiple personalities, one of whom is a Serial Killer and most of the movie takes place within his mind/a hallucination. The legal men are trying to determine the insane Malcolm Rivers' case.
At the end of John Doe: Vigilante, the titular Villain Protagonist abruptly concludes his How We Got Here-style interrogation by killing the Hero Antagonist detective who's been interviewing him through the whole film. It then turns out that said detective was actually the Dirty Cop responsible for a Chekhov's Gun crime shown in one of the flashbacks — a surefire way to wind up on Doe's Dexter-esque hit list.
Last Train to Freo's drama is drawn from the fact that not all the characters are strangers to each other and it's no coincidence that they're all in the same train car. There are two major Tomato Surprises. First, Simon and Lisa are not strangers, but are in fact a couple. They boarded the train separately in order to set up and kill The Tall Thug, who attacked Simon's brother and caused him brain damage. Second, The Tall Thug and Simon's brother were closeted lovers. The Tall Thug attacked Simon's brother during an argument; The Tall Thug wanted to come out, but his lover didn't. The Tall Thug got a short prison term after concocting a completely different story which Simon didn't contradict in court out of shame over his brother's sexual orientation.
At the end of Maverick the showdown between Brett and Cooper is resolved when the two stop pretending to not know each other and act as father and son.
Triangle starts with the protagonist having a crappy morning with her disabled son, and then in the next shot she is standing near a dock on the marina where she meets her friends while acting all confused. It seems like these 2 scenes happen within several minutes with nothing important happening in between, but the truth is that it's been more than a whole day between those 2 scenes, at least for the protagonist. Previously, she had been with her friends on a haunted ship where she ended up killing them, then traveled back in time to that morning, killed the past version of herself to replace her, but then her son got killed in a car accident so she went to the marina in order to return to the haunted ship where she hoped she would be able to travel back in time to save her son from dying. It's very likely that she's been stuck in an infinite series of Time Travel-induced Close-Enough Timeline loops in which she keeps killing her friends and her past-self in order to be reunited with her son, but then the inevitably recurring deaths of her son make her travel back in time again and again in futile attempts to save her son the next time, thus making her appearance on the marina a result of a convoluted Stable Time Loop.