This is an original movie prop, (not a replica) of the same type and from the same era as those used in this film, but there is no way to know for certain if this bill was actually used in this specific movie. Though it is a possibility, I am not making any claims whatsoever that this bill was ever used in this movie. It's an interesting piece from the Golden Age of Hollywood, and I felt this was a good place to post it. This type of bill was in Cairo's wallet and is briefly visible when Spade looks through the contents. The $1000 bills seen later are also variants of the same type. These reprints of obsolete 1915-20 era Mexican revolution currency were very common from the 1920s until the 1960s. Until then, it was prohibited by US laws to use actual US currency in films or TV shows.
