As for voiceovers, I've noticed that sometimes they'll announce something as fact in the voiceover, and then in the plot it will turn out never to have been true. They're not above lying in the voiceover, if it creates suspense... which it doesn't; it's like crying wolf.
Well, yes, they definitely make references to ways in which certain aspects of the plot *might* turn out, though perhaps they don't actually. But that's just a way to tease the audience - and that sort of ploy does successfully create suspense. And, yes, they'll also make references to what might be a belief at some point in a plot, but which might later turn out to have been deliberate misinformation given to a character or characters because they had been lied to - in which case it wasn't so much that the voiceover was "lying," per se, as it was reporting the facts as they were strongly believed to be within the plot at the time (like, say, Barnabas' belief that the Leviathans held Josette prisoner, but they only used that lie as a ploy to keep Barn under their thumb) - and that sort of "lie" is always explained within the plot in which it occured. But I've never honestly noticed where a statement made in a voiceover to, say, establish an offscreen plot fact (like, say, that PT Stokes was dead) because there hadn't been the time or need to establish it onscreen was contradicted. Or where a voiceover's clarification of a character's motivation was contradicted. Or where the voiceover built up that something was indeed going to absolutely happen only to have it not happen. If you're aware of instances like that, I'd love if you could cite some examples.