Have a nephew in the film/advertising/sound industry. Says the average Joe Soap has no clue as to what a heli sounds like so they go to a web site with sound tracks, ask for heli noise of engine or whatever and the first to hand cracks the nod. Then of course they stuff up, forget what sound was used first so put in something else.
Being a bit bit of a bike nutter, the same happens when motorcycles are used. Have heard Ducati 916/999's sounding like single cylinder dirt bikes.
Also get peeved in movies where people are able to stand up in executive jets like the Lear series. And to think these prats get paid gazillions more than we do
