There's no individual item that stands out as really strange, but the cumulative effect of lots of unfamiliar things would make the average 1930s pilot probably feel a bit overwhelmed.
Navaids such as VOR, DME and ILS would be new - not too difficult to get to grips with, but still unfamiliar, if not black magic!
The electrical system, with interior & exterior lighting, electric fuel pump, pitot heat & starter motor etc. would be new to most 1930s private pilots, as would VHF radio.
They would have to get used to paved runways, crosswind landings and tricycle landing gear - and they might be surprised by retractable gear and wobbly props. They would probably be delighted to have flaps and wheel brakes, though.
FBW