One of the more famous lines in movie history is:

We're not in Kansas anymore.

So just like Dorothy in the Wizard of Oz, how can you tell that you are no longer home.

1) People Talk Funny

For some of you, the local language won't be your first language. In this case, most of the words that will come out of people's mouths will sound like an alien gibberish. You, I feel sorry for, but not too much.
The people who I do feel sorry are the people who speak the same language as the natives, but can't understand a word they're saying because they've either butchered the language beyond belief or speak with an accent only comprehensible to an underwater sea-horse.
To the both of you I wish God speed. Remember, one day you'll look back and laugh at how you couldn't understand a thing people were saying.

2) People Look Different

After many years of knowing what everyone is "supposed to look like", all of a sudden people who defy your expectations crop up anywhere. The key here is to not get caught by too much surprise when you enter a train and realize that no one in the train looks like they are from your local village.

3) People Act Weird

You will meet people who think and act very differently from you. You probably won't understand their jokes or see the fun in what they consider a hobby or recreational activity. You might even be tempted to spend a lot of time complaining to your family members just "how weird and silly" everyone is. Don't do that. Try to figure out why they like what they like. You never know, you may just discover a new hobby.