While Danny Kaye worked hard to be able to accurately fake playing cornet (he practiced for months learning the fingering of the instrument), it was the real Red Nichols who provided all of the cornet playing for Kaye in this movie.
The exaggerated tango Danny Kaye did with the blonde Charleston dancer (Lizanne Truex) in the nightclub scene was not scripted. The rehearsals only called for her to do the Charleston, then flit offstage. During one of them Danny suddenly grabbed her and began hamming it up, with Lizanne quickly ad-libbing. Director Melville Shavelson liked it and added it to the routine.
Keep an eye out for a cameo by Bob Hope and the crack Danny Kaye makes about him, as he, Barbara Bel Geddes and a very young Tuesday Weld wait to get into the Brown Derby restaurant.
A contemporary article in The Hollywood Reporter noted Benny Goodman was to play himself in this film but negotiations fell through due to his salary demands.
When the story begins, in 1924, Red Nichols was aged 19, but is played by a 48 year-old Danny Kaye.