"Christ it was supposed to be a fun film and Steiger is far far from having a sense of humor" Henry Hathaway said about his star Rod Steiger.
A fifteen ton actual safe was used for the heist sequence. Rod Steiger and Michael Dante actually cracked the safe for the shooting, advised by technicians from the vault's manufacturer.
This was released less than six months before the strikingly similar heist film Ocean's Eleven (1960) (the original version starring Frank Sinatra and various members of his so-called "Rat Pack"). While "Oceans" was successful enough to merit a big budget remake and, in some circles, is considered a minor classic, "Thieves" came and went almost without notice and is mostly forgotten today.