If science fiction is about what we think the future will look like, an alternate history with a Point of Divergence in 1929 (when people from the future arrived bearing technological gifts) should look a lot like 1920s scifi. So a survey of the genre at that time reveals that my book will be full of this sort of nonsense:
hover-pack
particle accelerator-field generator
disembodied intelligence
improve conditions for the poor by giving them fish gills!
disintigration ray
robots with hollographic costumes
glass buildings
Sorbing (brain-draining)
rockets
gap between ruling and working class
giant dangerous animals (the fatal eggs)
freeze ray!
death ray
insanity ray
ray guns