Language would cause a lot of awkward situations.
Modern people casually use profanity that would have been considered very low-class in 1900. People in 1900 casually used racial epithets that would shock the time-traveller.
Automobiles were not unknown, but most people grew up with horses and horse-drawn vehicles. There was an entire vocabulary that is little-known today. You would be thought very strange if you did not know the difference between a “forelock” and a “fetlock”, or the difference between a “hansom” and a “plus-four”.
Social life was a lot more structured back then. People joined a lot of clubs. Nearly everyone went to church on Sunday. Even if they were not religious, it was often the only social life available in small towns.
If you did manage to secure gainful employment, and started making friends, you would find yourself under a lot of pressure to find someone nice, with whom to marry and start a family. For your own good, of course. There was no Social Security in those days, and you needed children, to support you in your old age.