Trivia: In the scene where Bing Crosby and Danny Kaye are escaping the club where the sisters are performing, you see Bing Crosby hail a cab. Not withstanding that there happens to be a cab in the alley, but moreover, when Bing "whistles" you can here that he wasn't able to do it. It comes out as a "flub" sound. Not really a mistake, but kinda funny.
Trivia: Ever wonder why Vera-Ellen is always shown in the movie wearing a high collar dress/shirt/pajama top/etc.? She was suffering from premature aging effects (she was only 33 at the time) from what is believed to have been anorexia. It showed predominantly in her chest and neck - hence, the desire for her to have her neck covered.