acceptability of "in a continent"

[Susanast]

Hello,
here´s a question generated by a translation from Czech: it was a professional CV of a singer who “sang on almost all the continents”. “On a continent” is definitely correct, the idea behind the preposition is that of standing ON a landmass (as opposed to being IN the water) I suppose – but can you say “in all the continents” when you actually mean IN various countries all over the world? (That is – since one “can say” almost anything – would you consider “in” grammatically acceptable?)

Thanks very much,

Zuzana

[Barb_D]

It sure sounds weird to me to hear "in a continent." I'd stick with "in a country" and "on a continent."