Can you tell me how to buy a high-speed ticket from Prague to Slovakia? Do I need to pay a border tax? Do I need to take a boat if I take a small road ?

I'm going back to Prague from Slovakia. They are all land routes, and the Czech Republic, Austria, Hungary, and Slovakia all buy highway fees at gas stations. You shouldn't have to buy it in the country where you originally rented the car. Most of their cars have their own annual highway fees. You can ask in advance.

Tickets for the highway in Slovakia can be bought at the highway gas station at the entrance or exit of the country. The lowest price is 10 euros (which is probably valid for 10 days).