Still not a mistake as such. Besides, I read that as 'what do you consider to be the biggest mistakes' not 'what don't you like?'
Continuity/geographical errors, characters responding to unsaid thoughts of other characters, and non-comedic hammerspace instances.
@Inks I agree with those types of errors, or historical inaccuracies. But. whats a non-comedic hammerspace? Im imagining a somber vastness where hammers come from....and also die in...
I see a 'mistake' as anything which turns readers off, so by definition it's personal to each reader. If we stick to universally recognised errors, all we can say is SPAG. And even then you get some people who will break SPAG rules on purpose for effect so... we're left with a tumbleweed thread.
My story is a supernatural thriller relating to out-of-body experiences and a murder, told from the perspective of the main character. It's split into two parts, with ten years between them. I think I'm going to stick with first-person present tense
Hammerspace is a relative term to pulling out impossible to conceal objects from pockets typically the pants. Someone hiding weapons like swords or wizard staffs and such, but I extend it to carrying a complete alchemy set or other tools of a trade while being completely unable to logically carry or pack such items. For instance a swordsman with a hidden claymore strapped on his back, yet can limbo, backflip and spin around like a pole-dancer.
I took the thread to mean 'mistakes' rather than mistakes. The only real mistakes could be SPAG issues, plot holes, continuity errors or errors in judgement ( a writer who makes false claims about a race, job, position, place, religion - they know nothing about. ) Real mistakes. Other than that it's all personal preference. I only picked first person present tense because on writer sites and book sites I see many a good novels getting wrecked through writers not being able to handle that combo. If someone could pull it off with a reasonably likable character I'd be fine with it. Most of the first person present tense characters I've run into have been hugely arrogant, crass, obnoxious, depressingly mean and narrow minded. Now this could still be called personal preference - but is it when you discover the author didn't mean for their character to come off as obnoxious?
I've seen it happen more in series fiction than stand alone novels. I've seen mc's ages change - one went from being 16 to 18 years old and back again in a series, I've seen siblings names flubbed - one went from Horace to Harold in between books, even past events can become severely altered.
Leaving actual mistakes aside ...bad grammar, clunky, un-attributed dialogue, totally inept research... here are a few things that make me (usually) dislike a novel: 1) Self-consciously experimental style. I like to get immersed in a story, and this detracts. For me. (Exceptions: E Annie Proulx and Terry Pratchett) 2) Characters who don't quite gel. Their behaviour is inconsistent for no good story reason. (Romances can be rife with this sort of thing. A hero who is standoffish one minute, gentle and caring the next, borderline brutal the next ...ooh how exciting. Not.) 3) Galloping pace. I'm not a person who wants to get to the end of a (good) story as quickly as possible. I want to savour the journey, and remember it later. 4) A feeling that I've read this story before—when I haven't.... 5) Plot holes. They truly bug me. 6) Bad transitions. You know the kind. You're reading along, and suddenly realise the author has changed to a different locale, or time, or even different characters, and you didn't realise this till halfway down the page when things totally stopped making sense. Which leads to: 7) The need to backtrack. The need to constantly go back to check if you missed something, because you're confused as a reader, and don't know what is going on.