History Film / Coherence

** Em's broken phone. [[spoiler:Hugh's phone is apparently broken in the same way in one of the other universes, but nobody can remember it. That's how the other characters realize that they're not in the right dimension.]] b

** [[spoiler: And in the end it turns out that staying together with someone only means that you will travel through realities together, not that you ever can or will return to the original reality.]]

* AllJustADream: Played with. When Em wakes up the next morning, she is kind of surprised that everybody reacted as if nothing has happened. Was she just dreaming? Turns out that [[spoiler:Em #2]] escaped from the bathroom unnoticed. Em's [[KilledToUpholdTheMasquerade plan]] failed.

* NeverSplitTheParty: Subverted twice when the group decides to stay together to check on their cars. [[spoiler:Em #1]] leaves the group to check out her own car, only to bump into [[spoiler:Kevin #2]]. Later [[spoiler:Em #2]] does the same mistake and gets knocked out by [[spoiler:Em #1]].

** The "door to nowhere" is introduced early on, but the name doesn't strike as [[MeaningfulName relevant]] until much later.

** After venturing outside for the first time, the party goers return inside and note that a glass has been broken that no one remembers breaking. [[spoiler:They've returned to a different version than their original house]].

* {{Improv}}: The film's dialog is largely improvised.

* WhamShot: The writing in the notepad. [[spoiler: ''Done with a different marker.'']]

* CellphonesAreUseless: The characters are isolated in the house with no phone reception or internet.

* AmbiguousSituation: It's not clear why Laurie has seen ''Rosewell'' but has no memory of Mike in the cast, while at the same time Mike is falsely convinced that Laurie was once a yoga instructor. This seems to line up with the comet's effect of making people have "false memories" of past events, but the events they misremember are well outside of the comet's one-night-only effect. Did previous comets muddle their memories, or is this just a mundane and coincidental foreshadowing of the supernatural events to come?

** Also he comes up with a plan to blackmail himself with a note about the one-night-stand he and Beth had ten years ago. However, he slips the note under the door [[FinaglesLaw for the wrong person to find]].

* BlackScreenOfDeath: On several occasions the movie suddenly cuts to black. It's being theorized that each time this happens, [[spoiler: the story moves to another/parallel house with different versions of the characters.]]

* BreadMilkEggsSquick: Beth mentions that her relaxation concoction contains a bunch of ingredients: echinacea, valerian root, ketamine.... When she hits the last one the other characters react exactly as you'd expect.
* CastingGag: Nicholas Brendon plays an actor who claims to have been in all four seasons of ''Roswell'', and his wife indicates in one scene that his career was derailed due to alcohol addiction. Of course, Nicholas Brendon was in all but one episode of the seven seasons of ''Buffy the Vampire Slayer'', and admitted in 2010 that he had a recurring problem with alcohol.

** Hugh's band-aid. First, it's made of cloth but later changes to regular.

* EncyclopediaExposita: The book Hugh's brother left which provides {{Info Dump}}s about quantum decoherence.
* EverybodyLives: No matter how hard [[spoiler:Em]] tries to sabotage this trope in the third act.
* EvilCounterpart: Mike and Em discuss the possibility of such thing. [[spoiler:And Em ultimately becomes one.]]

* ExtremelyShortTimespan: The plot spans over one night up until the next morning.

* ProperlyParanoid: Mike is suspicious of his alternate counterparts trying to kill him. And eventually one does attack. Might very well be a case of SelfFulfillingProphecy.

* SpotTheImposter: The group uses colored glow sticks to identify ''visitors''. [[spoiler:Much later the mismatching dice numbers and icons from the box make it clear that this approach failed.]]

* TrappedInAnotherWorld[=/=]YouCantGoHomeAgain: [[spoiler:Discussed by Em and Mike. Once characters pass the dark area they are randomly transported into {{Alternate Timeline}}s with little hope of returning to their homeworld. For Em it actually serves as a {{Foreshadowing}}.]]

* ProtagonistJourneyToVillain: [[spoiler:In the end, having realized she [[YouCantGoHomeAgain may never find her home reality again]], Em decides to search for a more pleasant reality, kill her counterpart there, and take over her life. It doesn't work.]]

* TrappedInAnotherWorld[=/=]YouCantGoHomeAgain: [[spoiler:Discussed by Em and Mike. Once characters pass the dark area they are randomly transported into {{Alternate Timeline}}s with little hope of returning to their homeworld.]]

* TheTunguskaEvent: Invoked by Em early on, when she shares what she read about weird comet events. Part of her story [[ChekhovsClassroom are important later]].

* TrappedInAnotherWorld / YouCantGoHomeAgain: [[spoiler:Discussed by Em and Mike. Once characters pass the dark area they are randomly transported into {{Alternate Timeline}}s with little hope of returning to their homeworld.]]