i am fascinated by how english native speakers confuse you're with your but non native dont usually have problems.
in spanish is normal to change the prounouns (le la los la) grammar rules depending of the region of spain making talking with people a little confusing https://en.wikipedia.org/wiki/Le%C3%ADsmo
Not a mistake but greek is gendered so hard that even the word for nobody has 3 different genders and it's very weird.
Also non-native speakers and especially english speakers consistently mess up every letter completely and it's kind of funny. I don't know what the fancy scientific terms are but the most obvious one is how no one pronounces gamma or delta right.