It was weird that the flashback sequences were undercranked like a silent movie. I always figured that the sped-up nature of the silent movies we've seen comes from playing them back at the later standard of 24 frames per second when originally they were presumably screened at a lower frame rate matching what they were filmed in (18 fps?). But this was made early enough in the era of talkies that people would've remembered the original playback speed -- yet here the flashbacks are deliberately undercranked, implying that even then, silent films were commonly perceived as playing faster than normal. I don't know what to make of that. (I wonder if it was done to give the flashback scenes a sense of being old, the way that later color films would do flashbacks in black and white or with a sepia tinge.)
I've read that the playback rate was governed by the guy cranking the camera and that there wasn't a set standard until sound came along and required synchronization. Sometimes these things are apocryphal but it sounds reasonable.