One thing I've seen appearing more often is using newer technologies to mimic older technologies of times past. The most common I've seen is the fake radio player.
The device is typically an old consumer radio that has had a little audio player installed within it that is connected to the speaker. The audio player is then playing music and sound of that time period on loop. This gives the illusion that the radio is receiving over-the-air radio broadcasts.
Now, some people may think that this is a cheap trick and that it is not authentic and thus not true to the historical setting.
I can see their point of view, for example I feel it would not be correct to demonstrate a television screen by replacing a CRT monitor with a more modern type of display such as a flat LCD screen.
However in this case I believe the output is true to its setting. Playing the current radio broadcasts on the device will place emphasis on how the device no longer fits within the current world and therefore be jarring and confusing to guests (not to mention licensing issues that can occur playing live broadcasts).
The device is showing it's “functional” state as it would do regularly in it's period. But most importantly, I believe it enhances the overall experience by placing guests deeper in the immersion of it's intended setting.
Is it a cheap trick and a gimmick? Yes. But it's one that does work if considered carefully and not overdone.