A Conundrum!

I'm confused. My copy of Jules Verne's Around The World in 80 Days shows Phileas Fogg and Passepartout in a hot air balloon when, in the novel, they never actually do, boats, trains and elephants yes. Hot air balloons no!! I know it's a commonly held belief that they do travel at least part of the way in a balloon, but although it's mentioned as a possibility, they never resort to it. Did the cover artist not read the book before they designed the artwork? Or at least ask someone what happened? Very peculiar!!