The open part of a pillow case MUST point towards the outside of the bed (I’m talking about a shared bed). I’m sure I have more.
The distinction, which IMHO that cite fails to adequately make clear, is that things like distance and time are continuous, rather than discrete, quantities. You can easily have fractional miles or fractional hours, so “less than 3 miles” for a distance of 2.8 miles or “less than 3 hours” for 2:55 are perfectly okay.
I get annoyingly pedantic about the names of airlines. I usually manage to refrain from correcting people, but I have to point out that the big airline headquartered in Atlanta spells their name “Delta Air Lines” – three words. Not “Airlines”.
And the smallish airline named after the 49th state is “Alaska Airlines”. Not “Alaskan Airlines”. Not “Alaska Air”. And most definitely not “Alaskan Air”. Lots of people seem to get the name of that airline wrong, maybe because they are relatively small and not as familiar to people on the East Coast.
I dislike when people misuse similar sounding words. Most recently, my sister was saying eminent when she meant imminent. But I know that many people dislike being corrected (and I make some effort in not being THAT GUY with my friends/family), so I asked if she wanted me to correct such things, and she said yes please.
I also dislike mispronunciations. Like, my wife consistently pronounces “spat” as “spate.” Words with alternative pronunciations - like integral - kinda bother me, as I think one of them must be “right.”
And I disfavor redundancies. My wife will say “a tad bit” or “bread roll.” But she does not wish me to be the 24/7 grammar/usage cop. And one need not always be ultra efficient in one’s language.
Use of apostrophes to make plurals irritate me.
I think my mom trained me to give up on correcting people. At a certain age, she started either adding Rs to names or dropping other consonants from them. And once she had said the odd pronunciation twice, there was no way it was ever going to leave her head.
For instance, the small box that the kids played games on was the Intendo.
I agree, but then, if I do say so myself, I’ve managed to turn annoying pedantry into an annoying art form. 
With a few common exceptions in informal contexts, I’m unreasonably bugged by mistakes in grammar, spelling, and punctuation. And yes, I’m going to go right ahead and call them “mistakes”, not “non-standard usages”
As for “well” and “good”, proper usage can sometimes be mistakenly thought incorrect. There is nothing wrong with saying “I’m good” in response to “how are you?” or if asked if you need help with anything. It has a significantly different meaning from “I’m well”. In the latter case, “well” is being used as an adjective modifying the subject, just like “good”.
In a similar vein, it drives me nuts when someone says “I feel badly”. No, you don’t. You feel bad. “Bad” is an adjective modifying the subject (it describes your emotional state), it’s not an adverb modifying the verb “feel”, as if you were physically feeling about for something and doing it badly.
Generally, “fewer” is used with discrete countable quantities, “less” with continuous ones. The sentence quoted below, “We all want fewer problems and less trouble with ‘fewer’ and ‘less’” illustrates this well.
It could be excused as an exception to the general rule if it’s regarded as a short form of “10 items or a lesser number”. But more importantly, it’s so common that it pretty much has to be tolerated, like grocers’ apostrophes. 
I’ll mention a couple of my own annoyances that have been discussed extensively on the board, and I’m certainly not trying to start another argument, but I think they’re good examples of being annoyingly pedantic.
One is what I regard as a widespread misunderstanding around the use of “literally” as an intensifier. As I see it, such usage should be considered to be creating a metaphor, and the writer or speaker should ask themselves if it’s an appropriate metaphor that has expressive value. Thus,
Good: “She literally glowed with happiness.”
Bad: “When I heard the news my head literally asploded!”
And don’t get me started on “I could care less”, which apparently describes some middling state of caring, in between not caring at all and caring a great deal. I don’t know why linguists like Pinker put themselves through such contortions to justify it as an acceptable variant of the correct expression that’s being used “ironically”. They seem to find it hard to acknowledge the simpler explanation that people just mishear things, thoughtlessly repeat the mishearing, and eventually it becomes commonplace and makes it into the written language. It’s not as if that’s never happened before!
It bugs me that people hyphenate where it is not appropriate. Examples:
Please print-out three copies of the report.
I’m going to pick-up some tacos for dinner.
Wrong, wrong, wrong! But it’s a futile battle.
Or use the hyphen to construct non-words, like “now available in-store”.
A news article recently stated that a child was “seven-years-old.”
Same here. There are already loads of words for damaging something very badly. Decimation, when used consistent with its historic application, provides more nuance.
But unlike so many others, I am delightfully pedantic, as opposed to annoyingly so.
I got a good citizen award in 3rd grade. I was up on stage with the principal and he introduced me. He mis-pronounced my last name (happens a lot). I corrected him, on stage in front of the audience.
My response is always, “not any more”!
THERE ARE TWO SPACES AFTER A PERIOD!
Oxford Comma 4 lyfe, yo!
Here’s another: A sweater is something you have to put on when your mother’s cold.
A slightly different one that drives me nuts (likely because I encounter it so often in my job) is when I ask a simple question, and someone answers a question other than the one I asked. Takes a couple of forms:
-Ask a question that can be answered yes/no, or with a specific number/date/etc. And instead of answering yes/no or with the simple, clear answer, the other person starts to tell you a freaking story.
-Ask a question the the other person doesn’t know the answer to or doesn’t want to admit the answer, and instead of saying “I don’t know” or giving the answer they don’t want to give they start telling you a bunch of stuff that is maybe somewhat related, but does not answer the specific question asked.
For whatever reason, people don’t seem to take it kindly when I respond, “Well, that’s a fine answer to a question other than the one I asked!”
Speaking of which: The phrase “I’m not sure” means “I think I have an answer, but I am not confident of its correctness”. It doesn’t mean, “this is the very first time I have ever heard of this topic and I have no idea what any of this means but I think saying ‘I don’t know’ makes me look weak”.
Nothing, or at least it doesn’t bother me. On the other hand “He has less dollars than I do” grates on my ear.
I must be missing something. What is wrong with that usage?
Lapis is the Latin root word for stone
False analogy from “seven-year-old child”?