Now we are all fantasy writers and readers, but even we need things to work right. They have to make sense. Magic is an exception, of course, along with creatures such as minotaurs or dragons. But there are some things you have to keep true or it drags the reader away from the actual story.
1) If you don't know anything about something, research. I know just enough about armor to be dangerous, so when I have to describe stuff, off to Google or the giant arms book my sister left me. I want things to make sense.
2) There is an author that we love that we just stopped reading because of some major real life type stuff that wasn't right, so don't lose readers this way. My example here is gas. There is some major disaster in this book and for 20 years the place has been in a downward spiral with no modern conveniences. But one of our heroes finds an ATV with gas in it and it started right up. For those who do not know, gas goes bad and lines clog if they sit too long. That's why your mower sounds so horrible after it sits all winter if you didn't drain the gas. It was hard to finish the book, especially with all the missteps with food that had come before. The stuff the author was messing up with could have been researched and explained, but they didn't explain it, which drew away from the story.
3) If something doesn't "work" in the "real world" explain how it works. So with the healing magic in my story a reader would wonder why healers just don't go around the world healing and saving everyone in my world. But I explain that away with the fact it takes something from the healer, so there is only so much they can do per day or for a dying person before killing themselves.
My suggestion is just make sure things work and make sense or you could pull someone from your story.
Happy Writing!