Hayato Sumino plays (the **** ouf of) Rhapsody in Blue

Sumino improvises throughout. Starting at 6:35 he plays a duet with himself on melodica. And at about 14:25 he plays a short upper register trill which, I'm told (there's a clip the points this out specifically), is an answer to a ringtone coming from somewhere in the audience.

You might want to compare this with Béla Fleck's banjo version, which I've linked here.