US dollar bills are all green and look similar, unlike in other countries where bills are differently colored and sized.
Using money that is all the same color.
Americans put a lot of ice in their drinks, while Europeans don't. This may be due to the "more is more" attitude in the US.
The US writes dates as month-day-year, while the rest of the world writes dates as day-month-year. This can be confusing for people from different countries.
The United States is not the only country in America. People from other countries often refer to the US as "the States" to avoid confusion.
Americans see prescription drug ads on TV, which is uncommon in other countries. In the UK, doctors recommend drugs, not the other way around.
Advertising prescription drugs all over the place.
Americans often display American flags in public places, which can be strange to people from other countries.
In the US, pharmacies are more like convenience stores than in Europe. They sell both drugs and junk food. This can be surprising to people from other countries.
Many Reddit users found it strange that bread in the US is often sweet. They are used to bread being less sweet in other countries.