The best things don’t always happen while you’re dancing, particulary if you’re trying to sing “The Best Things Happen While You’re Dancing” at the same time.
Irving Berlin composed and Robert Alton choreographed one solo (“Choreography”) for Donald O’Connor and one duet (“Best Things”) for O’Connor and Vera-Ellen. When Danny Kaye took over the role, it quickly became obvious that while Kaye was a good dancer, he lacked the technical skills required to carry a complicated solo. So, during the “Choreography” number, he sang the song and performed a few basic moves, then stepped to the side and let a professional take over.
That wouldn’t really work for a “falling in love” song like “Best Things.” So the hope was that Vera-Ellen could cover up—if not elevate—Danny’s dancing. Unfortunately, while rehearsing the number, Vera-Ellen injured a finger on her right hand while sliding on a rail. She went to the hospital the next day for X-rays and had to wear a splint on her finger for several days.
Rehearsing the number again three days later, this time it was Danny's turn to get hurt. While performing a swinging turn on a bar, he landed on the side of his right foot and turned his ankle. A medic tended to his injury on the scene.
Miraculously, the number turned out beautifully—by far Danny’s most accomplished dance on film. And somehow nobody got killed. Although if you watch really closely at the very end, as Vera-Ellen twirls behind a kneeling Kaye, she trips over his leg.