This is an interesting identification challenge. I have some knowledge of harmonicas or French harps, but it is not encyclopedic and my actual pieces are more recent than vintage. I wonder if again there were several different props used throughout the film? For example there are both “crushed” and “uncrushed” examples in the images. It has been a long time since I watched the actual movie so I am mainly going by the provided images.
There seem to be several distinct visual characteristics but it is difficult to find one real world example which brings them all together. In several images (1, 8, 11 and 13) the instrument shows a double row of holes or chambers. This would make it a tremolo harmonica with two reeds per hole. There are ten, double rows of holes as seen in images 8, 11, and 13. This is a possible, as the tremolo comes in several sizes; (I know of) 16, 20, 21, 22, 24, and28. The 24 hole version is pretty common and popular today. The 20,22, and 28 are rare today but I do not know what the situation was in the 1800s. The size 20 seems correct as it is about 4” long so it will fit well into the hand as shown in images 2 and 3. When hanging in images 4 and 5 one might estimate the length as compared to the distance between the buttonholes.
However there is another distinctive feature when we look at the back. The clearest image is image 10 (less so in 6) which show three “bays” on the top and bottom cover plates. These openings allow exhaled air to exit when the player blows into the chambers. These are also seen even when the harmonica has been crushed in images 9 and 12. There may be other makers of this style of cover plate but they are easily seen on the Hohner Blues Harp MS Harmonica. However that model is not a tremolo harmonica and has only a single row of chambers.
The cover plates in 3, 7 and 7 provide additional clues and difficulties in matching the elements. The end of the cover plates are semi-circular and the arc goes all the way to the outside edge of the plate. Most Hohners have the rectangle cover plates ends (which also normally have two points of attachment per end), but some models (i.e. Marine Band Blues Harp) do have arced ends with a single point of attachment. Conversely the MS Blues Harp has rectangular ends which is set back from the outer edge. Also image 7 provides the best visual of the stamped metal top cover plate but it is not detailed enough for me to find an exact match. Again there are German Hohner instruments which have similar stampings for the Grand Prix (Grand Prize) awards they earned in competitions and a pair of hands as a center element. The Hohner Marine Band versions are good examples which cover a long manufacturing range so there maybe a model which brings these elements together in a single model.
If there are additional images I would be interested in trying to take this investigation further.
