International rail crossings outnumber international airports by 18 to one (the airport in question being Prague), but both are outscored by the 30-plus international road crossings.
There are regular flights between Prague and other reasonably sized Czech cities, even more regular (and reasonably cheap) train services courtesy of Czech Railways, and a low-cost but highly dependable long-distance bus network. The road network is good, but drive defensively to counter the local addiction to excessive speeding.