In many movies, TV shows and books, we (the audience) experience a character's memories—often in a climax or the "revelation" scene—while they explain some secret or past action to another character. These moments are often depicted as flashbacks with real emotional impact laced into them. Sometimes the flashback scene is cut with snippets of dialogue to add information—details about the scene, the explainer's thoughts, or about how reliable the explainer is.
I started thinking about this especially because I was reminded (thanks to the recent Bryan Singer news) of the film The Usual Suspects, which effectively leverages quite a bit of of showing via flashbacks and telling via dialogue, the former of which include emotion and imagery that the audience perhaps perceives more vividly than the character being told about it (but less vividly than the character telling the story). The film plays with this concept in the sense that viewers see Keyser Söze in flashbacks without the audience or the listening character fully understanding who/what they're looking at and the implications thereof—until the twist ending.
So many movies use this flashback device, especially thriller/mystery/crime films that require a victim and/or perpetrator's perspective of a murder for the climactic revelation. It makes sense, of course, to use a flashback in a film (and often in a book), because it may be fairly dull for the audience to watch a character just discuss this huge climactic revelation. It's enlightening and interesting to the viewer, but it can raise problems: When this happens, we're presumably seeing more than what the character explaining the memory is saying to the listener, but it often seems that the listener absorbs the flashback scene's emotional nuance and complexity just as the audience does. The audience ostensibly has more information than the listener does, simply because the explainer (sometimes a killer to a detective or a villain with a secret to an MC) is likely unable to convey all of this simply by telling the listener about it via dialogue that we may not be "hearing." If, on the other hand, the flashback is what the "listener" is imagining when the other character explains, we are sometimes to understand that the perception of the scene may be unreliable, as in the case of The Usual Suspects (or Memento, for a different sort of example).
When this is done poorly, it's theatrically bothersome: There's a dramatic scene when the key characters (except, of course, the Authority Figure™ who could otherwise exonerate or condemn the explainer if only they were present at the time) hear the explainer telling everyone about his/her wrongdoing or secret past. In these moments, instead of absorbing via dialogue, we're often transported into the scene, in which apparently, either a) the confessor is able to express with perfect and irresolute accuracy what happened to everyone listening, or b) we're looking at the scene as if we're in one character's head—usually the MC or the person explaining, which is often assumed to be reliable as long as it's during the climax.
Sometimes the audience is treated to a dead character's perspective of the incident, a device that is often excused in cop shows with that belabored "genius detective" trope in which the main character is able to visualize with infallible clarity exactly what happened based on a blood smear and a bullet hole.
Some movies and books have built-in devices for ensuring that the listener is able to absorb more nuance—think Harry Potter and the Pensieve. Time travel can also be a device for showing MCs and "listeners" occurrences from the past. But devices like these usually don't work outside of fantasy and sci-fi genres. There's some overlap here and there too: The Prestige is a great film that also relies on flashbacky revelations (and just a dash of science fiction) in the climax, but because the "explainee" understands the principles of the "magic" at stake, it's more about catching the viewer up to what they may not have realized was possible within the world, rather than showing the audience something totally out of the realm of the listener's understanding.
And still other stories don't require the character to fully understand the emotional context: In The Fellowship of the Ring books, Gandalf explains via dialogue what he decides Frodo needs to know about the history of Sauron's rings—and indeed, Gandalf himself hasn't eye-witnessed many of the key moments he describes. In the movie, it's far more interesting to visually depict what happened, emotional nuance and all, and it doesn't particularly matter that Frodo doesn't pick up on it because a) the in-scene emotional nuance between the characters doesn't particularly impact his quest, and b) he's clever enough to pick up on some of it along the way from Aragorn, Elrond, Galadriel, Gollum, etc.
Related, and probably the root of these scenes, are Shakespearean-style revelations in which the audience has often already known about the dramatic irony all along. These are usually actual explanations in iambic pentameter, not immersive flashbacks, so we know that what's being explained may be skewed by the speaker, but we already know what really happened, so it's not a problem. This treatment is tolerable in stage performances, but can become less believable depending on the closeness of the medium to the characters' inner thoughts.
My further questions, then, are:
What other movies and books (especially those without some magical or futuristic "showing" device) execute flashback-reliant "explanations" well and leave few potential gaps around what the revelatory character says and what the explainer or explainee understands?
How is it achieved, especially if there is no magic or technology there to clarify the exlanation?
What are some other instances in which an explanation leaves a character with a purposefully inaccurate impression of the scene they are envisioning, and how then is the audience able to reach an accurate conclusion by the end of the story?